diff --git a/History.md b/History.md
index 45aecaf1b6..f6de08445e 100644
--- a/History.md
+++ b/History.md
@@ -1,5 +1,49 @@
 ## v.NEXT
 
+* Although Meteor does not recompile packages installed in `node_modules`
+  by default, compilation of specific npm packages (for example, to
+  support older browsers that the package author neglected) can now be
+  enabled in one of two ways:
+
+  * Clone the package repository into your application's `imports`
+    directory, make any modifications necessary, then use `npm install` to
+    link `the-package` into `node_modules`:
+    ```sh
+    meteor npm install imports/the-package
+    ```
+    Meteor will compile the contents of the package exposed via
+    `imports/the-package`, and this compiled code will be used when you
+    import `the-package` in any of the usual ways:
+    ```js
+    import stuff from "the-package"
+    require("the-package") === require("/imports/the-package")
+    import("the-package").then(...)
+    ```
+    This reuse of compiled code is the critical new feature that was added
+    in Meteor 1.6.2.
+
+  * Install the package normally with `meteor npm install the-package`,
+    then create a symbolic link *to* the installed package elsewhere in
+    your application, outside of `node_modules`:
+    ```sh
+    meteor npm install the-package
+    cd imports
+    ln -s ../node_modules/the-package .
+    ```
+    Again, Meteor will compile the contents of the package because they
+    are exposed outside of `node_modules`, and the compiled code will be
+    used whenever `the-package` is imported from `node_modules`.
+
+    > Note: this technique also works if you create symbolic links to
+      individual files, rather than linking the entire package directory.
+
+  In both cases, Meteor will compile the exposed code as if it was part of
+  your application, using whatever compiler plugins you have installed.
+  You can influence this compilation using `.babelrc` files or any other
+  techniques you would normally use to configure compilation of
+  application code. [PR #9771](https://github.com/meteor/meteor/pull/9771)
+  [Feature #6](https://github.com/meteor/meteor-feature-requests/issues/6)
+
 * Applications may now specify client and server entry point modules in a
   newly-supported `"meteor"` section of `package.json`:
   ```js
diff --git a/packages/modules-runtime/.npm/package/npm-shrinkwrap.json b/packages/modules-runtime/.npm/package/npm-shrinkwrap.json
index cab824928f..d79cb72b6b 100644
--- a/packages/modules-runtime/.npm/package/npm-shrinkwrap.json
+++ b/packages/modules-runtime/.npm/package/npm-shrinkwrap.json
@@ -2,9 +2,9 @@
   "lockfileVersion": 1,
   "dependencies": {
     "install": {
-      "version": "0.10.4",
-      "resolved": "https://registry.npmjs.org/install/-/install-0.10.4.tgz",
-      "integrity": "sha512-+IRyOastuPmLVx9zlVXJoKErSqz1Ma5at9A7S8yfsj3W+Kg95faPoh3bPDtMrZ/grz4PRmXzrswmlzfLlYyLOw=="
+      "version": "0.11.0",
+      "resolved": "https://registry.npmjs.org/install/-/install-0.11.0.tgz",
+      "integrity": "sha512-30UqvWKr/59SStU2/bRye4wT1S3mzjwa0oV+BxusB0neGqhxUrwLlnXDbt6QtIfBxCNWFqg+ARnGNjFj8XuV5A=="
     }
   }
 }
diff --git a/packages/modules-runtime/package.js b/packages/modules-runtime/package.js
index b0bbb12abe..96b9a42582 100644
--- a/packages/modules-runtime/package.js
+++ b/packages/modules-runtime/package.js
@@ -1,13 +1,13 @@
 Package.describe({
   name: "modules-runtime",
-  version: "0.9.2",
+  version: "0.10.0",
   summary: "CommonJS module system",
   git: "https://github.com/benjamn/install",
   documentation: "README.md"
 });
 
 Npm.depends({
-  install: "0.10.4"
+  install: "0.11.0"
 });
 
 Package.onUse(function(api) {
diff --git a/tools/cli/commands.js b/tools/cli/commands.js
index 2ae436df5c..5fef22f37f 100644
--- a/tools/cli/commands.js
+++ b/tools/cli/commands.js
@@ -582,7 +582,8 @@ main.registerCommand({
             return contents;
           }
         },
-        ignore: [/^local$/]
+        ignore: [/^local$/],
+        preserveSymlinks: true,
       });
     } catch (err) {
       Console.error("Could not create package: " + err.message);
@@ -750,7 +751,8 @@ main.registerCommand({
         return contents;
       }
     },
-    ignore: toIgnore
+    ignore: toIgnore,
+    preserveSymlinks: true,
   });
 
   // We are actually working with a new meteor project at this point, so
diff --git a/tools/fs/files.js b/tools/fs/files.js
index 260b531ce4..f5286fc165 100644
--- a/tools/fs/files.js
+++ b/tools/fs/files.js
@@ -297,6 +297,15 @@ function statOrNull(path, preserveSymlinks) {
   }
 }
 
+export function realpathOrNull(path) {
+  try {
+    return files.realpath(path);
+  } catch (e) {
+    if (e.code !== "ENOENT") throw e;
+    return null;
+  }
+}
+
 files.rm_recursive_async = (path) => {
   return new Promise((resolve, reject) => {
     rimraf(files.convertToOSPath(path), err => err
@@ -495,7 +504,7 @@ files.cp_r = function(from, to, options = {}) {
   files.mkdir_p(files.pathDirname(to));
 
   if (stat.isSymbolicLink()) {
-    files.symlink(files.readlink(from), to);
+    symlinkWithOverwrite(files.readlink(from), to);
 
   } else {
     // Create the file as readable and writable by everyone, and
@@ -517,6 +526,28 @@ files.cp_r = function(from, to, options = {}) {
   }
 };
 
+// create a symlink, overwriting the target link, file, or directory
+// if it exists
+export function symlinkWithOverwrite(source, target) {
+  try {
+    files.symlink(source, target);
+  } catch (e) {
+    if (e.code === "EEXIST") {
+      // overwrite existing link, file, or directory
+      files.rm_recursive(target);
+      files.symlink(source, target);
+    } else if (e.code === "EPERM" &&
+               process.platform === "win32") {
+      files.rm_recursive(target);
+      // This will work only if source refers to a directory, but that's a
+      // chance worth taking.
+      files.symlink(source, target, "junction");
+    } else {
+      throw e;
+    }
+  }
+}
+
 /**
  * Get every path in a directory recursively, treating symlinks as files
  * @param  {String} dir     The directory to walk, either relative to options.cwd or completely absolute
@@ -1003,7 +1034,9 @@ files.renameDirAlmostAtomically =
     // limitations, we'll resort to copying.
     if (forceCopy) {
       files.rm_recursive(toDir);
-      files.cp_r(fromDir, toDir);
+      files.cp_r(fromDir, toDir, {
+        preserveSymlinks: true,
+      });
     }
 
     // ... and take out the trash.
@@ -1750,7 +1783,7 @@ if (files.isWindowsLikeFilesystem()) {
     }
 
     if (! success) {
-      files.cp_r(from, to);
+      files.cp_r(from, to, { preserveSymlinks: true });
       files.rm_recursive(from);
     }
   };
diff --git a/tools/isobuild/builder.js b/tools/isobuild/builder.js
index fdb5973fba..b9566acf2b 100644
--- a/tools/isobuild/builder.js
+++ b/tools/isobuild/builder.js
@@ -1,6 +1,8 @@
 import assert from "assert";
 import {WatchSet, readAndWatchFile, sha1} from '../fs/watch.js';
-import files from '../fs/files.js';
+import files, {
+  symlinkWithOverwrite,
+} from '../fs/files.js';
 import NpmDiscards from './npm-discards.js';
 import {Profile} from '../tool-env/profile.js';
 import {
@@ -393,7 +395,10 @@ Previous builder: ${previousBuilder.outputPath}, this builder: ${outputPath}`
   // A version of copyDirectory that works better for copying node_modules
   // directories when symlinks are involved.
   copyNodeModulesDirectory(options) {
-    assert.strictEqual(files.pathBasename(options.from), "node_modules");
+    // Although the options.from directory should probably be a
+    // node_modules directory, the only essential precondition here is
+    // that the destination directory is a node_modules directory.
+    // assert.strictEqual(files.pathBasename(options.from), "node_modules");
     assert.strictEqual(files.pathBasename(options.to), "node_modules");
 
     if (options.symlink) {
@@ -805,28 +810,6 @@ function symlinkIfPossible(source, target) {
   }
 }
 
-// create a symlink, overwriting the target link, file, or directory
-// if it exists
-function symlinkWithOverwrite(source, target) {
-  try {
-    files.symlink(source, target);
-  } catch (e) {
-    if (e.code === "EEXIST") {
-      // overwrite existing link, file, or directory
-      files.rm_recursive(target);
-      files.symlink(source, target);
-    } else if (e.code === "EPERM" &&
-               process.platform === "win32") {
-      files.rm_recursive(target);
-      // This will work only if source refers to a directory, but that's a
-      // chance worth taking.
-      files.symlink(source, target, "junction");
-    } else {
-      throw e;
-    }
-  }
-}
-
 // Wrap slow methods into Profiler calls
 const slowBuilderMethods = [
   "_ensureDirectory",
diff --git a/tools/isobuild/bundler.js b/tools/isobuild/bundler.js
index 6b84a4a5e5..2cd07f968f 100644
--- a/tools/isobuild/bundler.js
+++ b/tools/isobuild/bundler.js
@@ -482,7 +482,7 @@ export class NodeModulesDirectory {
           return true;
         }
 
-        const real = realpathOrNull(path);
+        const real = files.realpathOrNull(path);
         if (typeof real === "string" &&
             real !== path) {
           // If node_modules/.bin/command is a symlink, determine the
@@ -522,15 +522,6 @@ export class NodeModulesDirectory {
   }
 }
 
-function realpathOrNull(path) {
-  try {
-    return files.realpath(path);
-  } catch (e) {
-    if (e.code !== "ENOENT") throw e;
-    return null;
-  }
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 // File
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/tools/isobuild/import-scanner.js b/tools/isobuild/import-scanner.js
index 57e8f6642b..b1163a8fda 100644
--- a/tools/isobuild/import-scanner.js
+++ b/tools/isobuild/import-scanner.js
@@ -18,9 +18,11 @@ import {
   pathNormalize,
   pathBasename,
   pathExtname,
+  pathDirname,
   pathIsAbsolute,
   convertToOSPath,
   convertToPosixPath,
+  realpathOrNull,
 } from "../fs/files.js";
 
 const {
@@ -32,6 +34,7 @@ const {
 import {
   optimisticReadFile,
   optimisticStatOrNull,
+  optimisticLStatOrNull,
   optimisticHashOrNull,
   shouldWatch,
 } from "../fs/optimistic.js";
@@ -134,6 +137,18 @@ const IMPORT_SCANNER_CACHE = new LRU({
   }
 });
 
+// Stub used for entry point modules within node_modules directories on
+// the server. These stub modules delegate to native Node evaluation by
+// calling module.useNode() immediately, but it's important that we have
+// something to include in the bundle so that parent modules have
+// something to resolve.
+const useNodeStub = {
+  dataString: "module.useNode();",
+  deps: Object.create(null),
+};
+useNodeStub.data = Buffer.from(useNodeStub.dataString, "utf8");
+useNodeStub.hash = sha1(useNodeStub.data);
+
 export default class ImportScanner {
   constructor({
     name,
@@ -151,6 +166,8 @@ export default class ImportScanner {
     this.nodeModulesPaths = nodeModulesPaths;
     this.watchSet = watchSet;
     this.absPathToOutputIndex = Object.create(null);
+    this.realPathToFiles = Object.create(null);
+    this.realPathCache = Object.create(null);
     this.allMissingModules = Object.create(null);
     this.outputFiles = [];
 
@@ -193,10 +210,12 @@ export default class ImportScanner {
       return file;
     }
 
-    absPath = absPath.toLowerCase();
-    const old = this.absPathToOutputIndex[absPath];
+    const absLowerPath = absPath.toLowerCase();
+
+    if (has(this.absPathToOutputIndex, absLowerPath)) {
+      const old = this.outputFiles[
+        this.absPathToOutputIndex[absLowerPath]];
 
-    if (old) {
       // If the old file is just an empty stub, let the new file take
       // precedence over it.
       if (old.implicit === true) {
@@ -213,7 +232,7 @@ export default class ImportScanner {
       }
 
     } else {
-      this.absPathToOutputIndex[absPath] =
+      this.absPathToOutputIndex[absLowerPath] =
         this.outputFiles.push(file) - 1;
 
       return file;
@@ -254,11 +273,82 @@ export default class ImportScanner {
         // multiple times with the same sourcePath. #6422
         this._combineFiles(this._getFile(absPath), file);
       }
+
+      this._addFileByRealPath(file, this._realPath(absPath));
     });
 
     return this;
   }
 
+  _addFileByRealPath(file, realPath) {
+    assert.ok(isObject(file));
+    assert.strictEqual(typeof realPath, "string");
+
+    if (! has(this.realPathToFiles, realPath)) {
+      this.realPathToFiles[realPath] = [];
+    }
+
+    const files = this.realPathToFiles[realPath];
+
+    if (files.indexOf(file) < 0) {
+      files.push(file);
+    }
+
+    return file;
+  }
+
+  _getInfoByRealPath(realPath) {
+    assert.strictEqual(typeof realPath, "string");
+    const files = this.realPathToFiles[realPath];
+    if (files && files.length > 0) {
+      const firstFile = files[0];
+      return {
+        data: firstFile.data,
+        dataString: firstFile.dataString,
+        hash: firstFile.hash,
+      };
+    }
+    return null;
+  }
+
+  _realPath(absPath) {
+    if (has(this.realPathCache, absPath)) {
+      return this.realPathCache[absPath];
+    }
+
+    let relativePath = pathRelative(this.sourceRoot, absPath);
+    if (relativePath.startsWith("..")) {
+      // If the absPath is outside this.sourceRoot, assume it's real.
+      return this.realPathCache[absPath] = absPath;
+    }
+
+    let foundSymbolicLink = false;
+
+    while (! foundSymbolicLink) {
+      const testPath = pathJoin(this.sourceRoot, relativePath);
+      if (testPath === this.sourceRoot) {
+        // Don't test the sourceRoot itself.
+        break;
+      }
+
+      const lstat = optimisticLStatOrNull(testPath);
+      if (lstat && lstat.isSymbolicLink()) {
+        foundSymbolicLink = true;
+        break
+      }
+
+      relativePath = pathDirname(relativePath);
+    }
+
+    if (foundSymbolicLink) {
+      // Call the actual realpathOrNull function only if there were any
+      // symlinks involved in the relative path within this.sourceRoot.
+      return this.realPathCache[absPath] = realpathOrNull(absPath);
+    }
+
+    return this.realPathCache[absPath] = absPath;
+  }
+
   // Make sure file.sourcePath is defined, and handle the possibility that
   // file.targetPath differs from file.sourcePath.
   _checkSourceAndTargetPaths(file) {
@@ -538,7 +628,45 @@ export default class ImportScanner {
     });
   }
 
+  _mergeFilesWithSameRealPath() {
+    Object.keys(this.realPathToFiles).forEach(realPath => {
+      const files = this.realPathToFiles[realPath];
+      if (! files || files.length < 2) {
+        return;
+      }
+
+      // We have multiple files that share the same realPath, so we need
+      // to figure out which one should actually contain the data, and
+      // which one(s) should merely be aliases to the data container.
+
+      let container = files[0];
+
+      // Take the first file inside node_modules as the container. If none
+      // found, default to the first file in the list. It's important to
+      // let node_modules files be the containers if possible, since some
+      // npm packages rely on having module IDs that appear to be within a
+      // node_modules directory.
+      files.some(file => {
+        if (file.absModuleId &&
+            file.absModuleId.startsWith("/node_modules/")) {
+          container = file;
+          return true;
+        }
+      });
+
+      // Alias every non-container file to container.absModuleId.
+      files.forEach(file => {
+        if (file !== container) {
+          file.alias = file.alias || {};
+          file.alias.absModuleId = container.absModuleId;
+        }
+      });
+    });
+  }
+
   getOutputFiles() {
+    this._mergeFilesWithSameRealPath();
+
     // Return all installable output files that are either eager or
     // imported (statically or dynamically).
     return this.outputFiles.filter(file => {
@@ -726,11 +854,7 @@ export default class ImportScanner {
          info.dynamic);
 
       const resolved = this._resolve(file, id, dynamic);
-      if (! resolved) {
-        return;
-      }
-
-      const absImportedPath = resolved.path;
+      const absImportedPath = resolved && resolved.path;
       if (! absImportedPath) {
         return;
       }
@@ -761,54 +885,15 @@ export default class ImportScanner {
         return;
       }
 
-      const absModuleId = this._getAbsModuleId(absImportedPath);
-      if (! absModuleId) {
-        // The given path cannot be installed on this architecture.
-        return;
-      }
-
-      info.absModuleId = absModuleId;
-
-      // If the module is not readable, _readModule may return
-      // null. Otherwise it will return an object with .data, .dataString,
-      // and .hash properties.
-      depFile = this._readModule(absImportedPath);
+      depFile = this._readDepFile(absImportedPath);
       if (! depFile) {
         return;
       }
 
-      depFile.type = "js"; // TODO Is this correct?
-      depFile.sourcePath = pathRelative(this.sourceRoot, absImportedPath);
-      depFile.absModuleId = absModuleId;
-      depFile.servePath = stripLeadingSlash(absModuleId);
-      depFile.lazy = true;
-      // Setting depFile.imported = false is necessary so that
-      // this._scanFile(depFile, dynamic) doesn't think the file has been
-      // scanned already and return immediately.
-      depFile.imported = false;
-
       // Append this file to the output array and record its index.
       this._addFile(absImportedPath, depFile);
 
-      // On the server, modules in node_modules directories will be
-      // handled natively by Node, so we don't need to build a
-      // meteorInstall-style bundle beyond the entry-point module.
-      if (! this.isWeb() &&
-          depFile.absModuleId.startsWith("/node_modules/") &&
-          // If optimistic functions care about this file, e.g. because it
-          // resides in a linked npm package, then we should allow it to
-          // be watched by including it in the server bundle by not
-          // returning here. Note that inclusion in the server bundle is
-          // an unnecessary consequence of this logic, since Node will
-          // still evaluate this module natively on the server. What we
-          // really care about is watching the file for changes.
-          ! shouldWatch(absImportedPath)) {
-        // Since we're not going to call this._scanFile(depFile, dynamic)
-        // below, this is our last chance to update depFile.imported.
-        depFile.imported = dynamic ? "dynamic" : true;
-        return;
-      }
-
+      // Recursively scan the module's imported dependencies.
       this._scanFile(depFile, dynamic);
     });
   }
@@ -889,6 +974,73 @@ export default class ImportScanner {
     return info;
   }
 
+  _readDepFile(absPath) {
+    const absModuleId = this._getAbsModuleId(absPath);
+    if (! absModuleId) {
+      // The given path cannot be installed on this architecture.
+      return null;
+    }
+
+    const realPath = this._realPath(absPath);
+
+    let depFile = this._getInfoByRealPath(realPath);
+    if (depFile) {
+      // If we already have a file with the same real path, use its data
+      // rather than reading the file again, or generating a stub. This
+      // logic enables selective compilation of node_modules in an elegant
+      // way: just expose the package directory within the application
+      // (outside of node_modules) using a symlink, so that it will be
+      // compiled as application code. When the package is imported from
+      // node_modules, the compiled version will be used instead of the
+      // raw version found in node_modules. See also:
+      // https://github.com/meteor/meteor-feature-requests/issues/6
+
+    } else if (! this.isWeb() &&
+               absModuleId.startsWith("/node_modules/")) {
+      // On the server, modules in node_modules directories will be
+      // handled natively by Node, so we just need to generate a stub
+      // module that calls module.useNode(), rather than calling
+      // this._readModule to read the actual module file. Note that
+      // useNodeStub includes an empty .deps property, which will make
+      // this._scanFile(depFile, dynamic) return immediately.
+      depFile = { ...useNodeStub };
+
+      // If optimistic functions care about this file, e.g. because it
+      // resides in a linked npm package, then we should allow it to
+      // be watched even though we are replacing it with a stub that
+      // merely calls module.useNode().
+      if (shouldWatch(absPath)) {
+        this.watchSet.addFile(
+          absPath,
+          optimisticHashOrNull(absPath),
+        );
+      }
+
+    } else {
+      // If the module is not readable, _readModule may return
+      // null. Otherwise it will return an object with .data,
+      // .dataString, and .hash properties.
+      depFile = this._readModule(absPath);
+      if (! depFile) {
+        return null;
+      }
+    }
+
+    depFile.type = "js"; // TODO Is this correct?
+    depFile.sourcePath = pathRelative(this.sourceRoot, absPath);
+    depFile.absModuleId = absModuleId;
+    depFile.servePath = stripLeadingSlash(absModuleId);
+    depFile.lazy = true;
+    // Setting depFile.imported = false is necessary so that
+    // this._scanFile(depFile, dynamic) doesn't think the file has been
+    // scanned already and return immediately.
+    depFile.imported = false;
+
+    this._addFileByRealPath(depFile, realPath);
+
+    return depFile;
+  }
+
   // Returns an absolute module identifier indicating where to install the
   // given file via meteorInstall. May return undefined if the file should
   // not be installed on the current architecture.
@@ -1232,6 +1384,7 @@ each([
   "_findImportedModuleIdentifiers",
   "_getAbsModuleId",
   "_addPkgJsonToOutput",
+  "_realPath",
   "_resolvePkgJsonBrowserAliases",
 ], funcName => {
   ImportScanner.prototype[funcName] = Profile(
diff --git a/tools/tests/apps/modules/imports/links/acorn/LICENSE b/tools/tests/apps/modules/imports/links/acorn/LICENSE
new file mode 100644
index 0000000000..2c0632b6a7
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/LICENSE
@@ -0,0 +1,19 @@
+Copyright (C) 2012-2018 by various contributors (see AUTHORS)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/tools/tests/apps/modules/imports/links/acorn/package.json b/tools/tests/apps/modules/imports/links/acorn/package.json
new file mode 100644
index 0000000000..1b47c365cc
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/package.json
@@ -0,0 +1,51 @@
+{
+  "name": "acorn",
+  "description": "ECMAScript parser",
+  "homepage": "https://github.com/acornjs/acorn",
+  "main": "src/index.js",
+  "version": "5.5.3",
+  "engines": {
+    "node": ">=0.4.0"
+  },
+  "maintainers": [
+    {
+      "name": "Marijn Haverbeke",
+      "email": "marijnh@gmail.com",
+      "web": "http://marijnhaverbeke.nl"
+    },
+    {
+      "name": "Ingvar Stepanyan",
+      "email": "me@rreverser.com",
+      "web": "http://rreverser.com/"
+    }
+  ],
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/acornjs/acorn.git"
+  },
+  "license": "MIT",
+  "scripts": {
+    "prepare": "npm test",
+    "test": "node test/run.js && node test/lint.js",
+    "pretest": "npm run build:main && npm run build:loose",
+    "test:test262": "node bin/run_test262.js",
+    "build": "npm run build:main && npm run build:walk && npm run build:loose && npm run build:bin",
+    "build:main": "rollup -c rollup/config.main.js",
+    "build:walk": "rollup -c rollup/config.walk.js",
+    "build:loose": "rollup -c rollup/config.loose.js && rollup -c rollup/config.loose_es.js",
+    "lint": "eslint src/"
+  },
+  "devDependencies": {
+    "eslint": "^4.10.0",
+    "eslint-config-standard": "^10.2.1",
+    "eslint-plugin-import": "^2.2.0",
+    "eslint-plugin-node": "^5.2.1",
+    "eslint-plugin-promise": "^3.5.0",
+    "eslint-plugin-standard": "^3.0.1",
+    "rollup": "^0.45.0",
+    "rollup-plugin-buble": "^0.16.0",
+    "test262": "git+https://github.com/tc39/test262.git#18c1e799a01cc976695983b61e225ce7959bdd91",
+    "test262-parser-runner": "^0.3.1",
+    "unicode-10.0.0": "^0.7.5"
+  }
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/.eslintrc b/tools/tests/apps/modules/imports/links/acorn/src/.eslintrc
new file mode 100644
index 0000000000..e636ee75db
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/.eslintrc
@@ -0,0 +1,33 @@
+{
+    "extends": [
+        "eslint:recommended",
+        "standard",
+        "plugin:import/errors",
+        "plugin:import/warnings"
+    ],
+    "rules": {
+        "curly": "off",
+        "eqeqeq": "off",
+        "indent": ["error", 2, { "SwitchCase": 0, "VariableDeclarator": 2, "CallExpression": { arguments: "off" } }],
+        "new-parens": "off",
+        "no-case-declarations": "off",
+        "no-cond-assign": "off",
+        "no-fallthrough": "off",
+        "no-labels": "off",
+        "no-mixed-operators": "off",
+        "no-return-assign": "off",
+        "no-unused-labels": "error",
+        "no-var": "error",
+        "object-curly-spacing": ["error", "never"],
+        "one-var": "off",
+        "quotes": ["error", "double"],
+        "semi-spacing": "off",
+        "space-before-function-paren": ["error", "never"]
+    },
+    "globals": {
+        "Packages": false
+    },
+    "plugins": [
+        "import"
+    ]
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/bin/.eslintrc b/tools/tests/apps/modules/imports/links/acorn/src/bin/.eslintrc
new file mode 100644
index 0000000000..2598b25f5f
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/bin/.eslintrc
@@ -0,0 +1,6 @@
+{
+    "extends": "../.eslintrc",
+    "rules": {
+        "no-console": "off"
+    }
+}
\ No newline at end of file
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/bin/acorn.js b/tools/tests/apps/modules/imports/links/acorn/src/bin/acorn.js
new file mode 100644
index 0000000000..d5fe42521a
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/bin/acorn.js
@@ -0,0 +1,62 @@
+import {basename} from "path"
+import {readFileSync as readFile} from "fs"
+import * as acorn from "acorn"
+
+let infile, forceFile, silent = false, compact = false, tokenize = false
+const options = {}
+
+function help(status) {
+  const print = (status == 0) ? console.log : console.error
+  print("usage: " + basename(process.argv[1]) + " [--ecma3|--ecma5|--ecma6|--ecma7|--ecma8|--ecma9|...|--ecma2015|--ecma2016|--ecma2017|--ecma2018|...]")
+  print("        [--tokenize] [--locations] [---allow-hash-bang] [--compact] [--silent] [--module] [--help] [--] [infile]")
+  process.exit(status)
+}
+
+for (let i = 2; i < process.argv.length; ++i) {
+  const arg = process.argv[i]
+  if ((arg == "-" || arg[0] != "-") && !infile) infile = arg
+  else if (arg == "--" && !infile && i + 2 == process.argv.length) forceFile = infile = process.argv[++i]
+  else if (arg == "--locations") options.locations = true
+  else if (arg == "--allow-hash-bang") options.allowHashBang = true
+  else if (arg == "--silent") silent = true
+  else if (arg == "--compact") compact = true
+  else if (arg == "--help") help(0)
+  else if (arg == "--tokenize") tokenize = true
+  else if (arg == "--module") options.sourceType = "module"
+  else {
+    let match = arg.match(/^--ecma(\d+)$/)
+    if (match)
+      options.ecmaVersion = +match[1]
+    else
+      help(1)
+  }
+}
+
+function run(code) {
+  let result
+  try {
+    if (!tokenize) {
+      result = acorn.parse(code, options)
+    } else {
+      result = []
+      let tokenizer = acorn.tokenizer(code, options), token
+      do {
+        token = tokenizer.getToken()
+        result.push(token)
+      } while (token.type != acorn.tokTypes.eof)
+    }
+  } catch (e) {
+    console.error(e.message)
+    process.exit(1)
+  }
+  if (!silent) console.log(JSON.stringify(result, null, compact ? null : 2))
+}
+
+if (forceFile || infile && infile != "-") {
+  run(readFile(infile, "utf8"))
+} else {
+  let code = ""
+  process.stdin.resume()
+  process.stdin.on("data", chunk => code += chunk)
+  process.stdin.on("end", () => run(code))
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/expression.js b/tools/tests/apps/modules/imports/links/acorn/src/expression.js
new file mode 100644
index 0000000000..79cd9b559f
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/expression.js
@@ -0,0 +1,909 @@
+// A recursive descent parser operates by defining functions for all
+// syntactic elements, and recursively calling those, each function
+// advancing the input stream and returning an AST node. Precedence
+// of constructs (for example, the fact that `!x[1]` means `!(x[1])`
+// instead of `(!x)[1]` is handled by the fact that the parser
+// function that parses unary prefix operators is called first, and
+// in turn calls the function that parses `[]` subscripts — that
+// way, it'll receive the node for `x[1]` already parsed, and wraps
+// *that* in the unary operator node.
+//
+// Acorn uses an [operator precedence parser][opp] to handle binary
+// operator precedence, because it is much more compact than using
+// the technique outlined above, which uses different, nesting
+// functions to specify precedence, for all of the ten binary
+// precedence levels that JavaScript defines.
+//
+// [opp]: http://en.wikipedia.org/wiki/Operator-precedence_parser
+
+import {types as tt} from "./tokentype"
+import {Parser} from "./state"
+import {DestructuringErrors} from "./parseutil"
+import {lineBreak} from "./whitespace"
+
+const pp = Parser.prototype
+
+// Check if property name clashes with already added.
+// Object/class getters and setters are not allowed to clash —
+// either with each other or with an init property — and in
+// strict mode, init properties are also not allowed to be repeated.
+
+pp.checkPropClash = function(prop, propHash, refDestructuringErrors) {
+  if (this.options.ecmaVersion >= 9 && prop.type === "SpreadElement")
+    return
+  if (this.options.ecmaVersion >= 6 && (prop.computed || prop.method || prop.shorthand))
+    return
+  let {key} = prop, name
+  switch (key.type) {
+  case "Identifier": name = key.name; break
+  case "Literal": name = String(key.value); break
+  default: return
+  }
+  let {kind} = prop
+  if (this.options.ecmaVersion >= 6) {
+    if (name === "__proto__" && kind === "init") {
+      if (propHash.proto) {
+        if (refDestructuringErrors && refDestructuringErrors.doubleProto < 0) refDestructuringErrors.doubleProto = key.start
+        // Backwards-compat kludge. Can be removed in version 6.0
+        else this.raiseRecoverable(key.start, "Redefinition of __proto__ property")
+      }
+      propHash.proto = true
+    }
+    return
+  }
+  name = "$" + name
+  let other = propHash[name]
+  if (other) {
+    let redefinition
+    if (kind === "init") {
+      redefinition = this.strict && other.init || other.get || other.set
+    } else {
+      redefinition = other.init || other[kind]
+    }
+    if (redefinition)
+      this.raiseRecoverable(key.start, "Redefinition of property")
+  } else {
+    other = propHash[name] = {
+      init: false,
+      get: false,
+      set: false
+    }
+  }
+  other[kind] = true
+}
+
+// ### Expression parsing
+
+// These nest, from the most general expression type at the top to
+// 'atomic', nondivisible expression types at the bottom. Most of
+// the functions will simply let the function(s) below them parse,
+// and, *if* the syntactic construct they handle is present, wrap
+// the AST node that the inner parser gave them in another node.
+
+// Parse a full expression. The optional arguments are used to
+// forbid the `in` operator (in for loops initalization expressions)
+// and provide reference for storing '=' operator inside shorthand
+// property assignment in contexts where both object expression
+// and object pattern might appear (so it's possible to raise
+// delayed syntax error at correct position).
+
+pp.parseExpression = function(noIn, refDestructuringErrors) {
+  let startPos = this.start, startLoc = this.startLoc
+  let expr = this.parseMaybeAssign(noIn, refDestructuringErrors)
+  if (this.type === tt.comma) {
+    let node = this.startNodeAt(startPos, startLoc)
+    node.expressions = [expr]
+    while (this.eat(tt.comma)) node.expressions.push(this.parseMaybeAssign(noIn, refDestructuringErrors))
+    return this.finishNode(node, "SequenceExpression")
+  }
+  return expr
+}
+
+// Parse an assignment expression. This includes applications of
+// operators like `+=`.
+
+pp.parseMaybeAssign = function(noIn, refDestructuringErrors, afterLeftParse) {
+  if (this.inGenerator && this.isContextual("yield")) return this.parseYield()
+
+  let ownDestructuringErrors = false, oldParenAssign = -1, oldTrailingComma = -1
+  if (refDestructuringErrors) {
+    oldParenAssign = refDestructuringErrors.parenthesizedAssign
+    oldTrailingComma = refDestructuringErrors.trailingComma
+    refDestructuringErrors.parenthesizedAssign = refDestructuringErrors.trailingComma = -1
+  } else {
+    refDestructuringErrors = new DestructuringErrors
+    ownDestructuringErrors = true
+  }
+
+  let startPos = this.start, startLoc = this.startLoc
+  if (this.type == tt.parenL || this.type == tt.name)
+    this.potentialArrowAt = this.start
+  let left = this.parseMaybeConditional(noIn, refDestructuringErrors)
+  if (afterLeftParse) left = afterLeftParse.call(this, left, startPos, startLoc)
+  if (this.type.isAssign) {
+    let node = this.startNodeAt(startPos, startLoc)
+    node.operator = this.value
+    node.left = this.type === tt.eq ? this.toAssignable(left, false, refDestructuringErrors) : left
+    if (!ownDestructuringErrors) DestructuringErrors.call(refDestructuringErrors)
+    refDestructuringErrors.shorthandAssign = -1 // reset because shorthand default was used correctly
+    this.checkLVal(left)
+    this.next()
+    node.right = this.parseMaybeAssign(noIn)
+    return this.finishNode(node, "AssignmentExpression")
+  } else {
+    if (ownDestructuringErrors) this.checkExpressionErrors(refDestructuringErrors, true)
+  }
+  if (oldParenAssign > -1) refDestructuringErrors.parenthesizedAssign = oldParenAssign
+  if (oldTrailingComma > -1) refDestructuringErrors.trailingComma = oldTrailingComma
+  return left
+}
+
+// Parse a ternary conditional (`?:`) operator.
+
+pp.parseMaybeConditional = function(noIn, refDestructuringErrors) {
+  let startPos = this.start, startLoc = this.startLoc
+  let expr = this.parseExprOps(noIn, refDestructuringErrors)
+  if (this.checkExpressionErrors(refDestructuringErrors)) return expr
+  if (this.eat(tt.question)) {
+    let node = this.startNodeAt(startPos, startLoc)
+    node.test = expr
+    node.consequent = this.parseMaybeAssign()
+    this.expect(tt.colon)
+    node.alternate = this.parseMaybeAssign(noIn)
+    return this.finishNode(node, "ConditionalExpression")
+  }
+  return expr
+}
+
+// Start the precedence parser.
+
+pp.parseExprOps = function(noIn, refDestructuringErrors) {
+  let startPos = this.start, startLoc = this.startLoc
+  let expr = this.parseMaybeUnary(refDestructuringErrors, false)
+  if (this.checkExpressionErrors(refDestructuringErrors)) return expr
+  return expr.start == startPos && expr.type === "ArrowFunctionExpression" ? expr : this.parseExprOp(expr, startPos, startLoc, -1, noIn)
+}
+
+// Parse binary operators with the operator precedence parsing
+// algorithm. `left` is the left-hand side of the operator.
+// `minPrec` provides context that allows the function to stop and
+// defer further parser to one of its callers when it encounters an
+// operator that has a lower precedence than the set it is parsing.
+
+pp.parseExprOp = function(left, leftStartPos, leftStartLoc, minPrec, noIn) {
+  let prec = this.type.binop
+  if (prec != null && (!noIn || this.type !== tt._in)) {
+    if (prec > minPrec) {
+      let logical = this.type === tt.logicalOR || this.type === tt.logicalAND
+      let op = this.value
+      this.next()
+      let startPos = this.start, startLoc = this.startLoc
+      let right = this.parseExprOp(this.parseMaybeUnary(null, false), startPos, startLoc, prec, noIn)
+      let node = this.buildBinary(leftStartPos, leftStartLoc, left, right, op, logical)
+      return this.parseExprOp(node, leftStartPos, leftStartLoc, minPrec, noIn)
+    }
+  }
+  return left
+}
+
+pp.buildBinary = function(startPos, startLoc, left, right, op, logical) {
+  let node = this.startNodeAt(startPos, startLoc)
+  node.left = left
+  node.operator = op
+  node.right = right
+  return this.finishNode(node, logical ? "LogicalExpression" : "BinaryExpression")
+}
+
+// Parse unary operators, both prefix and postfix.
+
+pp.parseMaybeUnary = function(refDestructuringErrors, sawUnary) {
+  let startPos = this.start, startLoc = this.startLoc, expr
+  if (this.inAsync && this.isContextual("await")) {
+    expr = this.parseAwait()
+    sawUnary = true
+  } else if (this.type.prefix) {
+    let node = this.startNode(), update = this.type === tt.incDec
+    node.operator = this.value
+    node.prefix = true
+    this.next()
+    node.argument = this.parseMaybeUnary(null, true)
+    this.checkExpressionErrors(refDestructuringErrors, true)
+    if (update) this.checkLVal(node.argument)
+    else if (this.strict && node.operator === "delete" &&
+             node.argument.type === "Identifier")
+      this.raiseRecoverable(node.start, "Deleting local variable in strict mode")
+    else sawUnary = true
+    expr = this.finishNode(node, update ? "UpdateExpression" : "UnaryExpression")
+  } else {
+    expr = this.parseExprSubscripts(refDestructuringErrors)
+    if (this.checkExpressionErrors(refDestructuringErrors)) return expr
+    while (this.type.postfix && !this.canInsertSemicolon()) {
+      let node = this.startNodeAt(startPos, startLoc)
+      node.operator = this.value
+      node.prefix = false
+      node.argument = expr
+      this.checkLVal(expr)
+      this.next()
+      expr = this.finishNode(node, "UpdateExpression")
+    }
+  }
+
+  if (!sawUnary && this.eat(tt.starstar))
+    return this.buildBinary(startPos, startLoc, expr, this.parseMaybeUnary(null, false), "**", false)
+  else
+    return expr
+}
+
+// Parse call, dot, and `[]`-subscript expressions.
+
+pp.parseExprSubscripts = function(refDestructuringErrors) {
+  let startPos = this.start, startLoc = this.startLoc
+  let expr = this.parseExprAtom(refDestructuringErrors)
+  let skipArrowSubscripts = expr.type === "ArrowFunctionExpression" && this.input.slice(this.lastTokStart, this.lastTokEnd) !== ")"
+  if (this.checkExpressionErrors(refDestructuringErrors) || skipArrowSubscripts) return expr
+  let result = this.parseSubscripts(expr, startPos, startLoc)
+  if (refDestructuringErrors && result.type === "MemberExpression") {
+    if (refDestructuringErrors.parenthesizedAssign >= result.start) refDestructuringErrors.parenthesizedAssign = -1
+    if (refDestructuringErrors.parenthesizedBind >= result.start) refDestructuringErrors.parenthesizedBind = -1
+  }
+  return result
+}
+
+pp.parseSubscripts = function(base, startPos, startLoc, noCalls) {
+  let maybeAsyncArrow = this.options.ecmaVersion >= 8 && base.type === "Identifier" && base.name === "async" &&
+      this.lastTokEnd == base.end && !this.canInsertSemicolon() && this.input.slice(base.start, base.end) === "async"
+  for (let computed;;) {
+    if ((computed = this.eat(tt.bracketL)) || this.eat(tt.dot)) {
+      let node = this.startNodeAt(startPos, startLoc)
+      node.object = base
+      node.property = computed ? this.parseExpression() : this.parseIdent(true)
+      node.computed = !!computed
+      if (computed) this.expect(tt.bracketR)
+      base = this.finishNode(node, "MemberExpression")
+    } else if (!noCalls && this.eat(tt.parenL)) {
+      let refDestructuringErrors = new DestructuringErrors, oldYieldPos = this.yieldPos, oldAwaitPos = this.awaitPos
+      this.yieldPos = 0
+      this.awaitPos = 0
+      let exprList = this.parseExprList(tt.parenR, this.options.ecmaVersion >= 8, false, refDestructuringErrors)
+      if (maybeAsyncArrow && !this.canInsertSemicolon() && this.eat(tt.arrow)) {
+        this.checkPatternErrors(refDestructuringErrors, false)
+        this.checkYieldAwaitInDefaultParams()
+        this.yieldPos = oldYieldPos
+        this.awaitPos = oldAwaitPos
+        return this.parseArrowExpression(this.startNodeAt(startPos, startLoc), exprList, true)
+      }
+      this.checkExpressionErrors(refDestructuringErrors, true)
+      this.yieldPos = oldYieldPos || this.yieldPos
+      this.awaitPos = oldAwaitPos || this.awaitPos
+      let node = this.startNodeAt(startPos, startLoc)
+      node.callee = base
+      node.arguments = exprList
+      base = this.finishNode(node, "CallExpression")
+    } else if (this.type === tt.backQuote) {
+      let node = this.startNodeAt(startPos, startLoc)
+      node.tag = base
+      node.quasi = this.parseTemplate({isTagged: true})
+      base = this.finishNode(node, "TaggedTemplateExpression")
+    } else {
+      return base
+    }
+  }
+}
+
+// Parse an atomic expression — either a single token that is an
+// expression, an expression started by a keyword like `function` or
+// `new`, or an expression wrapped in punctuation like `()`, `[]`,
+// or `{}`.
+
+pp.parseExprAtom = function(refDestructuringErrors) {
+  let node, canBeArrow = this.potentialArrowAt == this.start
+  switch (this.type) {
+  case tt._super:
+    if (!this.inFunction)
+      this.raise(this.start, "'super' outside of function or class")
+    node = this.startNode()
+    this.next()
+    // The `super` keyword can appear at below:
+    // SuperProperty:
+    //     super [ Expression ]
+    //     super . IdentifierName
+    // SuperCall:
+    //     super Arguments
+    if (this.type !== tt.dot && this.type !== tt.bracketL && this.type !== tt.parenL)
+      this.unexpected()
+    return this.finishNode(node, "Super")
+
+  case tt._this:
+    node = this.startNode()
+    this.next()
+    return this.finishNode(node, "ThisExpression")
+
+  case tt.name:
+    let startPos = this.start, startLoc = this.startLoc, containsEsc = this.containsEsc
+    let id = this.parseIdent(this.type !== tt.name)
+    if (this.options.ecmaVersion >= 8 && !containsEsc && id.name === "async" && !this.canInsertSemicolon() && this.eat(tt._function))
+      return this.parseFunction(this.startNodeAt(startPos, startLoc), false, false, true)
+    if (canBeArrow && !this.canInsertSemicolon()) {
+      if (this.eat(tt.arrow))
+        return this.parseArrowExpression(this.startNodeAt(startPos, startLoc), [id], false)
+      if (this.options.ecmaVersion >= 8 && id.name === "async" && this.type === tt.name && !containsEsc) {
+        id = this.parseIdent()
+        if (this.canInsertSemicolon() || !this.eat(tt.arrow))
+          this.unexpected()
+        return this.parseArrowExpression(this.startNodeAt(startPos, startLoc), [id], true)
+      }
+    }
+    return id
+
+  case tt.regexp:
+    let value = this.value
+    node = this.parseLiteral(value.value)
+    node.regex = {pattern: value.pattern, flags: value.flags}
+    return node
+
+  case tt.num: case tt.string:
+    return this.parseLiteral(this.value)
+
+  case tt._null: case tt._true: case tt._false:
+    node = this.startNode()
+    node.value = this.type === tt._null ? null : this.type === tt._true
+    node.raw = this.type.keyword
+    this.next()
+    return this.finishNode(node, "Literal")
+
+  case tt.parenL:
+    let start = this.start, expr = this.parseParenAndDistinguishExpression(canBeArrow)
+    if (refDestructuringErrors) {
+      if (refDestructuringErrors.parenthesizedAssign < 0 && !this.isSimpleAssignTarget(expr))
+        refDestructuringErrors.parenthesizedAssign = start
+      if (refDestructuringErrors.parenthesizedBind < 0)
+        refDestructuringErrors.parenthesizedBind = start
+    }
+    return expr
+
+  case tt.bracketL:
+    node = this.startNode()
+    this.next()
+    node.elements = this.parseExprList(tt.bracketR, true, true, refDestructuringErrors)
+    return this.finishNode(node, "ArrayExpression")
+
+  case tt.braceL:
+    return this.parseObj(false, refDestructuringErrors)
+
+  case tt._function:
+    node = this.startNode()
+    this.next()
+    return this.parseFunction(node, false)
+
+  case tt._class:
+    return this.parseClass(this.startNode(), false)
+
+  case tt._new:
+    return this.parseNew()
+
+  case tt.backQuote:
+    return this.parseTemplate()
+
+  default:
+    this.unexpected()
+  }
+}
+
+pp.parseLiteral = function(value) {
+  let node = this.startNode()
+  node.value = value
+  node.raw = this.input.slice(this.start, this.end)
+  this.next()
+  return this.finishNode(node, "Literal")
+}
+
+pp.parseParenExpression = function() {
+  this.expect(tt.parenL)
+  let val = this.parseExpression()
+  this.expect(tt.parenR)
+  return val
+}
+
+pp.parseParenAndDistinguishExpression = function(canBeArrow) {
+  let startPos = this.start, startLoc = this.startLoc, val, allowTrailingComma = this.options.ecmaVersion >= 8
+  if (this.options.ecmaVersion >= 6) {
+    this.next()
+
+    let innerStartPos = this.start, innerStartLoc = this.startLoc
+    let exprList = [], first = true, lastIsComma = false
+    let refDestructuringErrors = new DestructuringErrors, oldYieldPos = this.yieldPos, oldAwaitPos = this.awaitPos, spreadStart
+    this.yieldPos = 0
+    this.awaitPos = 0
+    while (this.type !== tt.parenR) {
+      first ? first = false : this.expect(tt.comma)
+      if (allowTrailingComma && this.afterTrailingComma(tt.parenR, true)) {
+        lastIsComma = true
+        break
+      } else if (this.type === tt.ellipsis) {
+        spreadStart = this.start
+        exprList.push(this.parseParenItem(this.parseRestBinding()))
+        if (this.type === tt.comma) this.raise(this.start, "Comma is not permitted after the rest element")
+        break
+      } else {
+        exprList.push(this.parseMaybeAssign(false, refDestructuringErrors, this.parseParenItem))
+      }
+    }
+    let innerEndPos = this.start, innerEndLoc = this.startLoc
+    this.expect(tt.parenR)
+
+    if (canBeArrow && !this.canInsertSemicolon() && this.eat(tt.arrow)) {
+      this.checkPatternErrors(refDestructuringErrors, false)
+      this.checkYieldAwaitInDefaultParams()
+      this.yieldPos = oldYieldPos
+      this.awaitPos = oldAwaitPos
+      return this.parseParenArrowList(startPos, startLoc, exprList)
+    }
+
+    if (!exprList.length || lastIsComma) this.unexpected(this.lastTokStart)
+    if (spreadStart) this.unexpected(spreadStart)
+    this.checkExpressionErrors(refDestructuringErrors, true)
+    this.yieldPos = oldYieldPos || this.yieldPos
+    this.awaitPos = oldAwaitPos || this.awaitPos
+
+    if (exprList.length > 1) {
+      val = this.startNodeAt(innerStartPos, innerStartLoc)
+      val.expressions = exprList
+      this.finishNodeAt(val, "SequenceExpression", innerEndPos, innerEndLoc)
+    } else {
+      val = exprList[0]
+    }
+  } else {
+    val = this.parseParenExpression()
+  }
+
+  if (this.options.preserveParens) {
+    let par = this.startNodeAt(startPos, startLoc)
+    par.expression = val
+    return this.finishNode(par, "ParenthesizedExpression")
+  } else {
+    return val
+  }
+}
+
+pp.parseParenItem = function(item) {
+  return item
+}
+
+pp.parseParenArrowList = function(startPos, startLoc, exprList) {
+  return this.parseArrowExpression(this.startNodeAt(startPos, startLoc), exprList)
+}
+
+// New's precedence is slightly tricky. It must allow its argument to
+// be a `[]` or dot subscript expression, but not a call — at least,
+// not without wrapping it in parentheses. Thus, it uses the noCalls
+// argument to parseSubscripts to prevent it from consuming the
+// argument list.
+
+const empty = []
+
+pp.parseNew = function() {
+  let node = this.startNode()
+  let meta = this.parseIdent(true)
+  if (this.options.ecmaVersion >= 6 && this.eat(tt.dot)) {
+    node.meta = meta
+    let containsEsc = this.containsEsc
+    node.property = this.parseIdent(true)
+    if (node.property.name !== "target" || containsEsc)
+      this.raiseRecoverable(node.property.start, "The only valid meta property for new is new.target")
+    if (!this.inFunction)
+      this.raiseRecoverable(node.start, "new.target can only be used in functions")
+    return this.finishNode(node, "MetaProperty")
+  }
+  let startPos = this.start, startLoc = this.startLoc
+  node.callee = this.parseSubscripts(this.parseExprAtom(), startPos, startLoc, true)
+  if (this.eat(tt.parenL)) node.arguments = this.parseExprList(tt.parenR, this.options.ecmaVersion >= 8, false)
+  else node.arguments = empty
+  return this.finishNode(node, "NewExpression")
+}
+
+// Parse template expression.
+
+pp.parseTemplateElement = function({isTagged}) {
+  let elem = this.startNode()
+  if (this.type === tt.invalidTemplate) {
+    if (!isTagged) {
+      this.raiseRecoverable(this.start, "Bad escape sequence in untagged template literal")
+    }
+    elem.value = {
+      raw: this.value,
+      cooked: null
+    }
+  } else {
+    elem.value = {
+      raw: this.input.slice(this.start, this.end).replace(/\r\n?/g, "\n"),
+      cooked: this.value
+    }
+  }
+  this.next()
+  elem.tail = this.type === tt.backQuote
+  return this.finishNode(elem, "TemplateElement")
+}
+
+pp.parseTemplate = function({isTagged = false} = {}) {
+  let node = this.startNode()
+  this.next()
+  node.expressions = []
+  let curElt = this.parseTemplateElement({isTagged})
+  node.quasis = [curElt]
+  while (!curElt.tail) {
+    this.expect(tt.dollarBraceL)
+    node.expressions.push(this.parseExpression())
+    this.expect(tt.braceR)
+    node.quasis.push(curElt = this.parseTemplateElement({isTagged}))
+  }
+  this.next()
+  return this.finishNode(node, "TemplateLiteral")
+}
+
+pp.isAsyncProp = function(prop) {
+  return !prop.computed && prop.key.type === "Identifier" && prop.key.name === "async" &&
+    (this.type === tt.name || this.type === tt.num || this.type === tt.string || this.type === tt.bracketL || this.type.keyword || (this.options.ecmaVersion >= 9 && this.type === tt.star)) &&
+    !lineBreak.test(this.input.slice(this.lastTokEnd, this.start))
+}
+
+// Parse an object literal or binding pattern.
+
+pp.parseObj = function(isPattern, refDestructuringErrors) {
+  let node = this.startNode(), first = true, propHash = {}
+  node.properties = []
+  this.next()
+  while (!this.eat(tt.braceR)) {
+    if (!first) {
+      this.expect(tt.comma)
+      if (this.afterTrailingComma(tt.braceR)) break
+    } else first = false
+
+    const prop = this.parseProperty(isPattern, refDestructuringErrors)
+    if (!isPattern) this.checkPropClash(prop, propHash, refDestructuringErrors)
+    node.properties.push(prop)
+  }
+  return this.finishNode(node, isPattern ? "ObjectPattern" : "ObjectExpression")
+}
+
+pp.parseProperty = function(isPattern, refDestructuringErrors) {
+  let prop = this.startNode(), isGenerator, isAsync, startPos, startLoc
+  if (this.options.ecmaVersion >= 9 && this.eat(tt.ellipsis)) {
+    if (isPattern) {
+      prop.argument = this.parseIdent(false)
+      if (this.type === tt.comma) {
+        this.raise(this.start, "Comma is not permitted after the rest element")
+      }
+      return this.finishNode(prop, "RestElement")
+    }
+    // To disallow parenthesized identifier via `this.toAssignable()`.
+    if (this.type === tt.parenL && refDestructuringErrors) {
+      if (refDestructuringErrors.parenthesizedAssign < 0) {
+        refDestructuringErrors.parenthesizedAssign = this.start
+      }
+      if (refDestructuringErrors.parenthesizedBind < 0) {
+        refDestructuringErrors.parenthesizedBind = this.start
+      }
+    }
+    // Parse argument.
+    prop.argument = this.parseMaybeAssign(false, refDestructuringErrors)
+    // To disallow trailing comma via `this.toAssignable()`.
+    if (this.type === tt.comma && refDestructuringErrors && refDestructuringErrors.trailingComma < 0) {
+      refDestructuringErrors.trailingComma = this.start
+    }
+    // Finish
+    return this.finishNode(prop, "SpreadElement")
+  }
+  if (this.options.ecmaVersion >= 6) {
+    prop.method = false
+    prop.shorthand = false
+    if (isPattern || refDestructuringErrors) {
+      startPos = this.start
+      startLoc = this.startLoc
+    }
+    if (!isPattern)
+      isGenerator = this.eat(tt.star)
+  }
+  let containsEsc = this.containsEsc
+  this.parsePropertyName(prop)
+  if (!isPattern && !containsEsc && this.options.ecmaVersion >= 8 && !isGenerator && this.isAsyncProp(prop)) {
+    isAsync = true
+    isGenerator = this.options.ecmaVersion >= 9 && this.eat(tt.star)
+    this.parsePropertyName(prop, refDestructuringErrors)
+  } else {
+    isAsync = false
+  }
+  this.parsePropertyValue(prop, isPattern, isGenerator, isAsync, startPos, startLoc, refDestructuringErrors, containsEsc)
+  return this.finishNode(prop, "Property")
+}
+
+pp.parsePropertyValue = function(prop, isPattern, isGenerator, isAsync, startPos, startLoc, refDestructuringErrors, containsEsc) {
+  if ((isGenerator || isAsync) && this.type === tt.colon)
+    this.unexpected()
+
+  if (this.eat(tt.colon)) {
+    prop.value = isPattern ? this.parseMaybeDefault(this.start, this.startLoc) : this.parseMaybeAssign(false, refDestructuringErrors)
+    prop.kind = "init"
+  } else if (this.options.ecmaVersion >= 6 && this.type === tt.parenL) {
+    if (isPattern) this.unexpected()
+    prop.kind = "init"
+    prop.method = true
+    prop.value = this.parseMethod(isGenerator, isAsync)
+  } else if (!isPattern && !containsEsc &&
+             this.options.ecmaVersion >= 5 && !prop.computed && prop.key.type === "Identifier" &&
+             (prop.key.name === "get" || prop.key.name === "set") &&
+             (this.type != tt.comma && this.type != tt.braceR)) {
+    if (isGenerator || isAsync) this.unexpected()
+    prop.kind = prop.key.name
+    this.parsePropertyName(prop)
+    prop.value = this.parseMethod(false)
+    let paramCount = prop.kind === "get" ? 0 : 1
+    if (prop.value.params.length !== paramCount) {
+      let start = prop.value.start
+      if (prop.kind === "get")
+        this.raiseRecoverable(start, "getter should have no params")
+      else
+        this.raiseRecoverable(start, "setter should have exactly one param")
+    } else {
+      if (prop.kind === "set" && prop.value.params[0].type === "RestElement")
+        this.raiseRecoverable(prop.value.params[0].start, "Setter cannot use rest params")
+    }
+  } else if (this.options.ecmaVersion >= 6 && !prop.computed && prop.key.type === "Identifier") {
+    this.checkUnreserved(prop.key)
+    prop.kind = "init"
+    if (isPattern) {
+      prop.value = this.parseMaybeDefault(startPos, startLoc, prop.key)
+    } else if (this.type === tt.eq && refDestructuringErrors) {
+      if (refDestructuringErrors.shorthandAssign < 0)
+        refDestructuringErrors.shorthandAssign = this.start
+      prop.value = this.parseMaybeDefault(startPos, startLoc, prop.key)
+    } else {
+      prop.value = prop.key
+    }
+    prop.shorthand = true
+  } else this.unexpected()
+}
+
+pp.parsePropertyName = function(prop) {
+  if (this.options.ecmaVersion >= 6) {
+    if (this.eat(tt.bracketL)) {
+      prop.computed = true
+      prop.key = this.parseMaybeAssign()
+      this.expect(tt.bracketR)
+      return prop.key
+    } else {
+      prop.computed = false
+    }
+  }
+  return prop.key = this.type === tt.num || this.type === tt.string ? this.parseExprAtom() : this.parseIdent(true)
+}
+
+// Initialize empty function node.
+
+pp.initFunction = function(node) {
+  node.id = null
+  if (this.options.ecmaVersion >= 6) {
+    node.generator = false
+    node.expression = false
+  }
+  if (this.options.ecmaVersion >= 8)
+    node.async = false
+}
+
+// Parse object or class method.
+
+pp.parseMethod = function(isGenerator, isAsync) {
+  let node = this.startNode(), oldInGen = this.inGenerator, oldInAsync = this.inAsync,
+      oldYieldPos = this.yieldPos, oldAwaitPos = this.awaitPos, oldInFunc = this.inFunction
+
+  this.initFunction(node)
+  if (this.options.ecmaVersion >= 6)
+    node.generator = isGenerator
+  if (this.options.ecmaVersion >= 8)
+    node.async = !!isAsync
+
+  this.inGenerator = node.generator
+  this.inAsync = node.async
+  this.yieldPos = 0
+  this.awaitPos = 0
+  this.inFunction = true
+  this.enterFunctionScope()
+
+  this.expect(tt.parenL)
+  node.params = this.parseBindingList(tt.parenR, false, this.options.ecmaVersion >= 8)
+  this.checkYieldAwaitInDefaultParams()
+  this.parseFunctionBody(node, false)
+
+  this.inGenerator = oldInGen
+  this.inAsync = oldInAsync
+  this.yieldPos = oldYieldPos
+  this.awaitPos = oldAwaitPos
+  this.inFunction = oldInFunc
+  return this.finishNode(node, "FunctionExpression")
+}
+
+// Parse arrow function expression with given parameters.
+
+pp.parseArrowExpression = function(node, params, isAsync) {
+  let oldInGen = this.inGenerator, oldInAsync = this.inAsync,
+      oldYieldPos = this.yieldPos, oldAwaitPos = this.awaitPos, oldInFunc = this.inFunction
+
+  this.enterFunctionScope()
+  this.initFunction(node)
+  if (this.options.ecmaVersion >= 8)
+    node.async = !!isAsync
+
+  this.inGenerator = false
+  this.inAsync = node.async
+  this.yieldPos = 0
+  this.awaitPos = 0
+  this.inFunction = true
+
+  node.params = this.toAssignableList(params, true)
+  this.parseFunctionBody(node, true)
+
+  this.inGenerator = oldInGen
+  this.inAsync = oldInAsync
+  this.yieldPos = oldYieldPos
+  this.awaitPos = oldAwaitPos
+  this.inFunction = oldInFunc
+  return this.finishNode(node, "ArrowFunctionExpression")
+}
+
+// Parse function body and check parameters.
+
+pp.parseFunctionBody = function(node, isArrowFunction) {
+  let isExpression = isArrowFunction && this.type !== tt.braceL
+  let oldStrict = this.strict, useStrict = false
+
+  if (isExpression) {
+    node.body = this.parseMaybeAssign()
+    node.expression = true
+    this.checkParams(node, false)
+  } else {
+    let nonSimple = this.options.ecmaVersion >= 7 && !this.isSimpleParamList(node.params)
+    if (!oldStrict || nonSimple) {
+      useStrict = this.strictDirective(this.end)
+      // If this is a strict mode function, verify that argument names
+      // are not repeated, and it does not try to bind the words `eval`
+      // or `arguments`.
+      if (useStrict && nonSimple)
+        this.raiseRecoverable(node.start, "Illegal 'use strict' directive in function with non-simple parameter list")
+    }
+    // Start a new scope with regard to labels and the `inFunction`
+    // flag (restore them to their old value afterwards).
+    let oldLabels = this.labels
+    this.labels = []
+    if (useStrict) this.strict = true
+
+    // Add the params to varDeclaredNames to ensure that an error is thrown
+    // if a let/const declaration in the function clashes with one of the params.
+    this.checkParams(node, !oldStrict && !useStrict && !isArrowFunction && this.isSimpleParamList(node.params))
+    node.body = this.parseBlock(false)
+    node.expression = false
+    this.adaptDirectivePrologue(node.body.body)
+    this.labels = oldLabels
+  }
+  this.exitFunctionScope()
+
+  if (this.strict && node.id) {
+    // Ensure the function name isn't a forbidden identifier in strict mode, e.g. 'eval'
+    this.checkLVal(node.id, "none")
+  }
+  this.strict = oldStrict
+}
+
+pp.isSimpleParamList = function(params) {
+  for (let param of params)
+    if (param.type !== "Identifier") return false
+  return true
+}
+
+// Checks function params for various disallowed patterns such as using "eval"
+// or "arguments" and duplicate parameters.
+
+pp.checkParams = function(node, allowDuplicates) {
+  let nameHash = {}
+  for (let param of node.params)
+    this.checkLVal(param, "var", allowDuplicates ? null : nameHash)
+}
+
+// Parses a comma-separated list of expressions, and returns them as
+// an array. `close` is the token type that ends the list, and
+// `allowEmpty` can be turned on to allow subsequent commas with
+// nothing in between them to be parsed as `null` (which is needed
+// for array literals).
+
+pp.parseExprList = function(close, allowTrailingComma, allowEmpty, refDestructuringErrors) {
+  let elts = [], first = true
+  while (!this.eat(close)) {
+    if (!first) {
+      this.expect(tt.comma)
+      if (allowTrailingComma && this.afterTrailingComma(close)) break
+    } else first = false
+
+    let elt
+    if (allowEmpty && this.type === tt.comma)
+      elt = null
+    else if (this.type === tt.ellipsis) {
+      elt = this.parseSpread(refDestructuringErrors)
+      if (refDestructuringErrors && this.type === tt.comma && refDestructuringErrors.trailingComma < 0)
+        refDestructuringErrors.trailingComma = this.start
+    } else {
+      elt = this.parseMaybeAssign(false, refDestructuringErrors)
+    }
+    elts.push(elt)
+  }
+  return elts
+}
+
+pp.checkUnreserved = function({start, end, name}) {
+  if (this.inGenerator && name === "yield")
+    this.raiseRecoverable(start, "Can not use 'yield' as identifier inside a generator")
+  if (this.inAsync && name === "await")
+    this.raiseRecoverable(start, "Can not use 'await' as identifier inside an async function")
+  if (this.isKeyword(name))
+    this.raise(start, `Unexpected keyword '${name}'`)
+  if (this.options.ecmaVersion < 6 &&
+    this.input.slice(start, end).indexOf("\\") != -1) return
+  const re = this.strict ? this.reservedWordsStrict : this.reservedWords
+  if (re.test(name)) {
+    if (!this.inAsync && name === "await")
+      this.raiseRecoverable(start, "Can not use keyword 'await' outside an async function")
+    this.raiseRecoverable(start, `The keyword '${name}' is reserved`)
+  }
+}
+
+// Parse the next token as an identifier. If `liberal` is true (used
+// when parsing properties), it will also convert keywords into
+// identifiers.
+
+pp.parseIdent = function(liberal, isBinding) {
+  let node = this.startNode()
+  if (liberal && this.options.allowReserved == "never") liberal = false
+  if (this.type === tt.name) {
+    node.name = this.value
+  } else if (this.type.keyword) {
+    node.name = this.type.keyword
+
+    // To fix https://github.com/acornjs/acorn/issues/575
+    // `class` and `function` keywords push new context into this.context.
+    // But there is no chance to pop the context if the keyword is consumed as an identifier such as a property name.
+    // If the previous token is a dot, this does not apply because the context-managing code already ignored the keyword
+    if ((node.name === "class" || node.name === "function") &&
+        (this.lastTokEnd !== this.lastTokStart + 1 || this.input.charCodeAt(this.lastTokStart) !== 46)) {
+      this.context.pop()
+    }
+  } else {
+    this.unexpected()
+  }
+  this.next()
+  this.finishNode(node, "Identifier")
+  if (!liberal) this.checkUnreserved(node)
+  return node
+}
+
+// Parses yield expression inside generator.
+
+pp.parseYield = function() {
+  if (!this.yieldPos) this.yieldPos = this.start
+
+  let node = this.startNode()
+  this.next()
+  if (this.type == tt.semi || this.canInsertSemicolon() || (this.type != tt.star && !this.type.startsExpr)) {
+    node.delegate = false
+    node.argument = null
+  } else {
+    node.delegate = this.eat(tt.star)
+    node.argument = this.parseMaybeAssign()
+  }
+  return this.finishNode(node, "YieldExpression")
+}
+
+pp.parseAwait = function() {
+  if (!this.awaitPos) this.awaitPos = this.start
+
+  let node = this.startNode()
+  this.next()
+  node.argument = this.parseMaybeUnary(null, true)
+  return this.finishNode(node, "AwaitExpression")
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/identifier.js b/tools/tests/apps/modules/imports/links/acorn/src/identifier.js
new file mode 100644
index 0000000000..5b6553b604
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/identifier.js
@@ -0,0 +1,87 @@
+// Reserved word lists for various dialects of the language
+
+export const reservedWords = {
+  3: "abstract boolean byte char class double enum export extends final float goto implements import int interface long native package private protected public short static super synchronized throws transient volatile",
+  5: "class enum extends super const export import",
+  6: "enum",
+  strict: "implements interface let package private protected public static yield",
+  strictBind: "eval arguments"
+}
+
+// And the keywords
+
+const ecma5AndLessKeywords = "break case catch continue debugger default do else finally for function if return switch throw try var while with null true false instanceof typeof void delete new in this"
+
+export const keywords = {
+  5: ecma5AndLessKeywords,
+  6: ecma5AndLessKeywords + " const class extends export import super"
+}
+
+export const keywordRelationalOperator = /^in(stanceof)?$/
+
+// ## Character categories
+
+// Big ugly regular expressions that match characters in the
+// whitespace, identifier, and identifier-start categories. These
+// are only applied when a character is found to actually have a
+// code point above 128.
+// Generated by `bin/generate-identifier-regex.js`.
+
+let nonASCIIidentifierStartChars = "\xaa\xb5\xba\xc0-\xd6\xd8-\xf6\xf8-\u02c1\u02c6-\u02d1\u02e0-\u02e4\u02ec\u02ee\u0370-\u0374\u0376\u0377\u037a-\u037d\u037f\u0386\u0388-\u038a\u038c\u038e-\u03a1\u03a3-\u03f5\u03f7-\u0481\u048a-\u052f\u0531-\u0556\u0559\u0561-\u0587\u05d0-\u05ea\u05f0-\u05f2\u0620-\u064a\u066e\u066f\u0671-\u06d3\u06d5\u06e5\u06e6\u06ee\u06ef\u06fa-\u06fc\u06ff\u0710\u0712-\u072f\u074d-\u07a5\u07b1\u07ca-\u07ea\u07f4\u07f5\u07fa\u0800-\u0815\u081a\u0824\u0828\u0840-\u0858\u0860-\u086a\u08a0-\u08b4\u08b6-\u08bd\u0904-\u0939\u093d\u0950\u0958-\u0961\u0971-\u0980\u0985-\u098c\u098f\u0990\u0993-\u09a8\u09aa-\u09b0\u09b2\u09b6-\u09b9\u09bd\u09ce\u09dc\u09dd\u09df-\u09e1\u09f0\u09f1\u09fc\u0a05-\u0a0a\u0a0f\u0a10\u0a13-\u0a28\u0a2a-\u0a30\u0a32\u0a33\u0a35\u0a36\u0a38\u0a39\u0a59-\u0a5c\u0a5e\u0a72-\u0a74\u0a85-\u0a8d\u0a8f-\u0a91\u0a93-\u0aa8\u0aaa-\u0ab0\u0ab2\u0ab3\u0ab5-\u0ab9\u0abd\u0ad0\u0ae0\u0ae1\u0af9\u0b05-\u0b0c\u0b0f\u0b10\u0b13-\u0b28\u0b2a-\u0b30\u0b32\u0b33\u0b35-\u0b39\u0b3d\u0b5c\u0b5d\u0b5f-\u0b61\u0b71\u0b83\u0b85-\u0b8a\u0b8e-\u0b90\u0b92-\u0b95\u0b99\u0b9a\u0b9c\u0b9e\u0b9f\u0ba3\u0ba4\u0ba8-\u0baa\u0bae-\u0bb9\u0bd0\u0c05-\u0c0c\u0c0e-\u0c10\u0c12-\u0c28\u0c2a-\u0c39\u0c3d\u0c58-\u0c5a\u0c60\u0c61\u0c80\u0c85-\u0c8c\u0c8e-\u0c90\u0c92-\u0ca8\u0caa-\u0cb3\u0cb5-\u0cb9\u0cbd\u0cde\u0ce0\u0ce1\u0cf1\u0cf2\u0d05-\u0d0c\u0d0e-\u0d10\u0d12-\u0d3a\u0d3d\u0d4e\u0d54-\u0d56\u0d5f-\u0d61\u0d7a-\u0d7f\u0d85-\u0d96\u0d9a-\u0db1\u0db3-\u0dbb\u0dbd\u0dc0-\u0dc6\u0e01-\u0e30\u0e32\u0e33\u0e40-\u0e46\u0e81\u0e82\u0e84\u0e87\u0e88\u0e8a\u0e8d\u0e94-\u0e97\u0e99-\u0e9f\u0ea1-\u0ea3\u0ea5\u0ea7\u0eaa\u0eab\u0ead-\u0eb0\u0eb2\u0eb3\u0ebd\u0ec0-\u0ec4\u0ec6\u0edc-\u0edf\u0f00\u0f40-\u0f47\u0f49-\u0f6c\u0f88-\u0f8c\u1000-\u102a\u103f\u1050-\u1055\u105a-\u105d\u1061\u1065\u1066\u106e-\u1070\u1075-\u1081\u108e\u10a0-\u10c5\u10c7\u10cd\u10d0-\u10fa\u10fc-\u1248\u124a-\u124d\u1250-\u1256\u1258\u125a-\u125d\u1260-\u1288\u128a-\u128d\u1290-\u12b0\u12b2-\u12b5\u12b8-\u12be\u12c0\u12c2-\u12c5\u12c8-\u12d6\u12d8-\u1310\u1312-\u1315\u1318-\u135a\u1380-\u138f\u13a0-\u13f5\u13f8-\u13fd\u1401-\u166c\u166f-\u167f\u1681-\u169a\u16a0-\u16ea\u16ee-\u16f8\u1700-\u170c\u170e-\u1711\u1720-\u1731\u1740-\u1751\u1760-\u176c\u176e-\u1770\u1780-\u17b3\u17d7\u17dc\u1820-\u1877\u1880-\u18a8\u18aa\u18b0-\u18f5\u1900-\u191e\u1950-\u196d\u1970-\u1974\u1980-\u19ab\u19b0-\u19c9\u1a00-\u1a16\u1a20-\u1a54\u1aa7\u1b05-\u1b33\u1b45-\u1b4b\u1b83-\u1ba0\u1bae\u1baf\u1bba-\u1be5\u1c00-\u1c23\u1c4d-\u1c4f\u1c5a-\u1c7d\u1c80-\u1c88\u1ce9-\u1cec\u1cee-\u1cf1\u1cf5\u1cf6\u1d00-\u1dbf\u1e00-\u1f15\u1f18-\u1f1d\u1f20-\u1f45\u1f48-\u1f4d\u1f50-\u1f57\u1f59\u1f5b\u1f5d\u1f5f-\u1f7d\u1f80-\u1fb4\u1fb6-\u1fbc\u1fbe\u1fc2-\u1fc4\u1fc6-\u1fcc\u1fd0-\u1fd3\u1fd6-\u1fdb\u1fe0-\u1fec\u1ff2-\u1ff4\u1ff6-\u1ffc\u2071\u207f\u2090-\u209c\u2102\u2107\u210a-\u2113\u2115\u2118-\u211d\u2124\u2126\u2128\u212a-\u2139\u213c-\u213f\u2145-\u2149\u214e\u2160-\u2188\u2c00-\u2c2e\u2c30-\u2c5e\u2c60-\u2ce4\u2ceb-\u2cee\u2cf2\u2cf3\u2d00-\u2d25\u2d27\u2d2d\u2d30-\u2d67\u2d6f\u2d80-\u2d96\u2da0-\u2da6\u2da8-\u2dae\u2db0-\u2db6\u2db8-\u2dbe\u2dc0-\u2dc6\u2dc8-\u2dce\u2dd0-\u2dd6\u2dd8-\u2dde\u3005-\u3007\u3021-\u3029\u3031-\u3035\u3038-\u303c\u3041-\u3096\u309b-\u309f\u30a1-\u30fa\u30fc-\u30ff\u3105-\u312e\u3131-\u318e\u31a0-\u31ba\u31f0-\u31ff\u3400-\u4db5\u4e00-\u9fea\ua000-\ua48c\ua4d0-\ua4fd\ua500-\ua60c\ua610-\ua61f\ua62a\ua62b\ua640-\ua66e\ua67f-\ua69d\ua6a0-\ua6ef\ua717-\ua71f\ua722-\ua788\ua78b-\ua7ae\ua7b0-\ua7b7\ua7f7-\ua801\ua803-\ua805\ua807-\ua80a\ua80c-\ua822\ua840-\ua873\ua882-\ua8b3\ua8f2-\ua8f7\ua8fb\ua8fd\ua90a-\ua925\ua930-\ua946\ua960-\ua97c\ua984-\ua9b2\ua9cf\ua9e0-\ua9e4\ua9e6-\ua9ef\ua9fa-\ua9fe\uaa00-\uaa28\uaa40-\uaa42\uaa44-\uaa4b\uaa60-\uaa76\uaa7a\uaa7e-\uaaaf\uaab1\uaab5\uaab6\uaab9-\uaabd\uaac0\uaac2\uaadb-\uaadd\uaae0-\uaaea\uaaf2-\uaaf4\uab01-\uab06\uab09-\uab0e\uab11-\uab16\uab20-\uab26\uab28-\uab2e\uab30-\uab5a\uab5c-\uab65\uab70-\uabe2\uac00-\ud7a3\ud7b0-\ud7c6\ud7cb-\ud7fb\uf900-\ufa6d\ufa70-\ufad9\ufb00-\ufb06\ufb13-\ufb17\ufb1d\ufb1f-\ufb28\ufb2a-\ufb36\ufb38-\ufb3c\ufb3e\ufb40\ufb41\ufb43\ufb44\ufb46-\ufbb1\ufbd3-\ufd3d\ufd50-\ufd8f\ufd92-\ufdc7\ufdf0-\ufdfb\ufe70-\ufe74\ufe76-\ufefc\uff21-\uff3a\uff41-\uff5a\uff66-\uffbe\uffc2-\uffc7\uffca-\uffcf\uffd2-\uffd7\uffda-\uffdc"
+let nonASCIIidentifierChars = "\u200c\u200d\xb7\u0300-\u036f\u0387\u0483-\u0487\u0591-\u05bd\u05bf\u05c1\u05c2\u05c4\u05c5\u05c7\u0610-\u061a\u064b-\u0669\u0670\u06d6-\u06dc\u06df-\u06e4\u06e7\u06e8\u06ea-\u06ed\u06f0-\u06f9\u0711\u0730-\u074a\u07a6-\u07b0\u07c0-\u07c9\u07eb-\u07f3\u0816-\u0819\u081b-\u0823\u0825-\u0827\u0829-\u082d\u0859-\u085b\u08d4-\u08e1\u08e3-\u0903\u093a-\u093c\u093e-\u094f\u0951-\u0957\u0962\u0963\u0966-\u096f\u0981-\u0983\u09bc\u09be-\u09c4\u09c7\u09c8\u09cb-\u09cd\u09d7\u09e2\u09e3\u09e6-\u09ef\u0a01-\u0a03\u0a3c\u0a3e-\u0a42\u0a47\u0a48\u0a4b-\u0a4d\u0a51\u0a66-\u0a71\u0a75\u0a81-\u0a83\u0abc\u0abe-\u0ac5\u0ac7-\u0ac9\u0acb-\u0acd\u0ae2\u0ae3\u0ae6-\u0aef\u0afa-\u0aff\u0b01-\u0b03\u0b3c\u0b3e-\u0b44\u0b47\u0b48\u0b4b-\u0b4d\u0b56\u0b57\u0b62\u0b63\u0b66-\u0b6f\u0b82\u0bbe-\u0bc2\u0bc6-\u0bc8\u0bca-\u0bcd\u0bd7\u0be6-\u0bef\u0c00-\u0c03\u0c3e-\u0c44\u0c46-\u0c48\u0c4a-\u0c4d\u0c55\u0c56\u0c62\u0c63\u0c66-\u0c6f\u0c81-\u0c83\u0cbc\u0cbe-\u0cc4\u0cc6-\u0cc8\u0cca-\u0ccd\u0cd5\u0cd6\u0ce2\u0ce3\u0ce6-\u0cef\u0d00-\u0d03\u0d3b\u0d3c\u0d3e-\u0d44\u0d46-\u0d48\u0d4a-\u0d4d\u0d57\u0d62\u0d63\u0d66-\u0d6f\u0d82\u0d83\u0dca\u0dcf-\u0dd4\u0dd6\u0dd8-\u0ddf\u0de6-\u0def\u0df2\u0df3\u0e31\u0e34-\u0e3a\u0e47-\u0e4e\u0e50-\u0e59\u0eb1\u0eb4-\u0eb9\u0ebb\u0ebc\u0ec8-\u0ecd\u0ed0-\u0ed9\u0f18\u0f19\u0f20-\u0f29\u0f35\u0f37\u0f39\u0f3e\u0f3f\u0f71-\u0f84\u0f86\u0f87\u0f8d-\u0f97\u0f99-\u0fbc\u0fc6\u102b-\u103e\u1040-\u1049\u1056-\u1059\u105e-\u1060\u1062-\u1064\u1067-\u106d\u1071-\u1074\u1082-\u108d\u108f-\u109d\u135d-\u135f\u1369-\u1371\u1712-\u1714\u1732-\u1734\u1752\u1753\u1772\u1773\u17b4-\u17d3\u17dd\u17e0-\u17e9\u180b-\u180d\u1810-\u1819\u18a9\u1920-\u192b\u1930-\u193b\u1946-\u194f\u19d0-\u19da\u1a17-\u1a1b\u1a55-\u1a5e\u1a60-\u1a7c\u1a7f-\u1a89\u1a90-\u1a99\u1ab0-\u1abd\u1b00-\u1b04\u1b34-\u1b44\u1b50-\u1b59\u1b6b-\u1b73\u1b80-\u1b82\u1ba1-\u1bad\u1bb0-\u1bb9\u1be6-\u1bf3\u1c24-\u1c37\u1c40-\u1c49\u1c50-\u1c59\u1cd0-\u1cd2\u1cd4-\u1ce8\u1ced\u1cf2-\u1cf4\u1cf7-\u1cf9\u1dc0-\u1df9\u1dfb-\u1dff\u203f\u2040\u2054\u20d0-\u20dc\u20e1\u20e5-\u20f0\u2cef-\u2cf1\u2d7f\u2de0-\u2dff\u302a-\u302f\u3099\u309a\ua620-\ua629\ua66f\ua674-\ua67d\ua69e\ua69f\ua6f0\ua6f1\ua802\ua806\ua80b\ua823-\ua827\ua880\ua881\ua8b4-\ua8c5\ua8d0-\ua8d9\ua8e0-\ua8f1\ua900-\ua909\ua926-\ua92d\ua947-\ua953\ua980-\ua983\ua9b3-\ua9c0\ua9d0-\ua9d9\ua9e5\ua9f0-\ua9f9\uaa29-\uaa36\uaa43\uaa4c\uaa4d\uaa50-\uaa59\uaa7b-\uaa7d\uaab0\uaab2-\uaab4\uaab7\uaab8\uaabe\uaabf\uaac1\uaaeb-\uaaef\uaaf5\uaaf6\uabe3-\uabea\uabec\uabed\uabf0-\uabf9\ufb1e\ufe00-\ufe0f\ufe20-\ufe2f\ufe33\ufe34\ufe4d-\ufe4f\uff10-\uff19\uff3f"
+
+const nonASCIIidentifierStart = new RegExp("[" + nonASCIIidentifierStartChars + "]")
+const nonASCIIidentifier = new RegExp("[" + nonASCIIidentifierStartChars + nonASCIIidentifierChars + "]")
+
+nonASCIIidentifierStartChars = nonASCIIidentifierChars = null
+
+// These are a run-length and offset encoded representation of the
+// >0xffff code points that are a valid part of identifiers. The
+// offset starts at 0x10000, and each pair of numbers represents an
+// offset to the next range, and then a size of the range. They were
+// generated by bin/generate-identifier-regex.js
+
+// eslint-disable-next-line comma-spacing
+const astralIdentifierStartCodes = [0,11,2,25,2,18,2,1,2,14,3,13,35,122,70,52,268,28,4,48,48,31,14,29,6,37,11,29,3,35,5,7,2,4,43,157,19,35,5,35,5,39,9,51,157,310,10,21,11,7,153,5,3,0,2,43,2,1,4,0,3,22,11,22,10,30,66,18,2,1,11,21,11,25,71,55,7,1,65,0,16,3,2,2,2,26,45,28,4,28,36,7,2,27,28,53,11,21,11,18,14,17,111,72,56,50,14,50,785,52,76,44,33,24,27,35,42,34,4,0,13,47,15,3,22,0,2,0,36,17,2,24,85,6,2,0,2,3,2,14,2,9,8,46,39,7,3,1,3,21,2,6,2,1,2,4,4,0,19,0,13,4,159,52,19,3,54,47,21,1,2,0,185,46,42,3,37,47,21,0,60,42,86,25,391,63,32,0,257,0,11,39,8,0,22,0,12,39,3,3,55,56,264,8,2,36,18,0,50,29,113,6,2,1,2,37,22,0,698,921,103,110,18,195,2749,1070,4050,582,8634,568,8,30,114,29,19,47,17,3,32,20,6,18,881,68,12,0,67,12,65,1,31,6124,20,754,9486,286,82,395,2309,106,6,12,4,8,8,9,5991,84,2,70,2,1,3,0,3,1,3,3,2,11,2,0,2,6,2,64,2,3,3,7,2,6,2,27,2,3,2,4,2,0,4,6,2,339,3,24,2,24,2,30,2,24,2,30,2,24,2,30,2,24,2,30,2,24,2,7,4149,196,60,67,1213,3,2,26,2,1,2,0,3,0,2,9,2,3,2,0,2,0,7,0,5,0,2,0,2,0,2,2,2,1,2,0,3,0,2,0,2,0,2,0,2,0,2,1,2,0,3,3,2,6,2,3,2,3,2,0,2,9,2,16,6,2,2,4,2,16,4421,42710,42,4148,12,221,3,5761,15,7472,3104,541]
+
+// eslint-disable-next-line comma-spacing
+const astralIdentifierCodes = [509,0,227,0,150,4,294,9,1368,2,2,1,6,3,41,2,5,0,166,1,1306,2,54,14,32,9,16,3,46,10,54,9,7,2,37,13,2,9,52,0,13,2,49,13,10,2,4,9,83,11,7,0,161,11,6,9,7,3,57,0,2,6,3,1,3,2,10,0,11,1,3,6,4,4,193,17,10,9,87,19,13,9,214,6,3,8,28,1,83,16,16,9,82,12,9,9,84,14,5,9,423,9,280,9,41,6,2,3,9,0,10,10,47,15,406,7,2,7,17,9,57,21,2,13,123,5,4,0,2,1,2,6,2,0,9,9,19719,9,135,4,60,6,26,9,1016,45,17,3,19723,1,5319,4,4,5,9,7,3,6,31,3,149,2,1418,49,513,54,5,49,9,0,15,0,23,4,2,14,1361,6,2,16,3,6,2,1,2,4,2214,6,110,6,6,9,792487,239]
+
+// This has a complexity linear to the value of the code. The
+// assumption is that looking up astral identifier characters is
+// rare.
+function isInAstralSet(code, set) {
+  let pos = 0x10000
+  for (let i = 0; i < set.length; i += 2) {
+    pos += set[i]
+    if (pos > code) return false
+    pos += set[i + 1]
+    if (pos >= code) return true
+  }
+}
+
+// Test whether a given character code starts an identifier.
+
+export function isIdentifierStart(code, astral) {
+  if (code < 65) return code === 36
+  if (code < 91) return true
+  if (code < 97) return code === 95
+  if (code < 123) return true
+  if (code <= 0xffff) return code >= 0xaa && nonASCIIidentifierStart.test(String.fromCharCode(code))
+  if (astral === false) return false
+  return isInAstralSet(code, astralIdentifierStartCodes)
+}
+
+// Test whether a given character is part of an identifier.
+
+export function isIdentifierChar(code, astral) {
+  if (code < 48) return code === 36
+  if (code < 58) return true
+  if (code < 65) return false
+  if (code < 91) return true
+  if (code < 97) return code === 95
+  if (code < 123) return true
+  if (code <= 0xffff) return code >= 0xaa && nonASCIIidentifier.test(String.fromCharCode(code))
+  if (astral === false) return false
+  return isInAstralSet(code, astralIdentifierStartCodes) || isInAstralSet(code, astralIdentifierCodes)
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/index.js b/tools/tests/apps/modules/imports/links/acorn/src/index.js
new file mode 100644
index 0000000000..aaf664da6b
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/index.js
@@ -0,0 +1,78 @@
+// Acorn is a tiny, fast JavaScript parser written in JavaScript.
+//
+// Acorn was written by Marijn Haverbeke, Ingvar Stepanyan, and
+// various contributors and released under an MIT license.
+//
+// Git repositories for Acorn are available at
+//
+//     http://marijnhaverbeke.nl/git/acorn
+//     https://github.com/acornjs/acorn.git
+//
+// Please use the [github bug tracker][ghbt] to report issues.
+//
+// [ghbt]: https://github.com/acornjs/acorn/issues
+//
+// This file defines the main parser interface. The library also comes
+// with a [error-tolerant parser][dammit] and an
+// [abstract syntax tree walker][walk], defined in other files.
+//
+// [dammit]: acorn_loose.js
+// [walk]: util/walk.js
+
+import {Parser} from "./state"
+import "./parseutil"
+import "./statement"
+import "./lval"
+import "./expression"
+import "./location"
+import "./scope"
+
+export {Parser, plugins} from "./state"
+export {defaultOptions} from "./options"
+export {Position, SourceLocation, getLineInfo} from "./locutil"
+export {Node} from "./node"
+export {TokenType, types as tokTypes, keywords as keywordTypes} from "./tokentype"
+export {TokContext, types as tokContexts} from "./tokencontext"
+export {isIdentifierChar, isIdentifierStart} from "./identifier"
+export {Token} from "./tokenize"
+export {isNewLine, lineBreak, lineBreakG, nonASCIIwhitespace} from "./whitespace"
+
+export const version = "5.5.3"
+
+// The main exported interface (under `self.acorn` when in the
+// browser) is a `parse` function that takes a code string and
+// returns an abstract syntax tree as specified by [Mozilla parser
+// API][api].
+//
+// [api]: https://developer.mozilla.org/en-US/docs/SpiderMonkey/Parser_API
+
+export function parse(input, options) {
+  return new Parser(options, input).parse()
+}
+
+// This function tries to parse a single expression at a given
+// offset in a string. Useful for parsing mixed-language formats
+// that embed JavaScript expressions.
+
+export function parseExpressionAt(input, pos, options) {
+  let p = new Parser(options, input, pos)
+  p.nextToken()
+  return p.parseExpression()
+}
+
+// Acorn is organized as a tokenizer and a recursive-descent parser.
+// The `tokenizer` export provides an interface to the tokenizer.
+
+export function tokenizer(input, options) {
+  return new Parser(options, input)
+}
+
+// This is a terrible kludge to support the existing, pre-ES6
+// interface where the loose parser module retroactively adds exports
+// to this module.
+export let parse_dammit, LooseParser, pluginsLoose // eslint-disable-line camelcase
+export function addLooseExports(parse, Parser, plugins) {
+  parse_dammit = parse // eslint-disable-line camelcase
+  LooseParser = Parser
+  pluginsLoose = plugins
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/location.js b/tools/tests/apps/modules/imports/links/acorn/src/location.js
new file mode 100644
index 0000000000..99e71234cc
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/location.js
@@ -0,0 +1,26 @@
+import {Parser} from "./state"
+import {Position, getLineInfo} from "./locutil"
+
+const pp = Parser.prototype
+
+// This function is used to raise exceptions on parse errors. It
+// takes an offset integer (into the current `input`) to indicate
+// the location of the error, attaches the position to the end
+// of the error message, and then raises a `SyntaxError` with that
+// message.
+
+pp.raise = function(pos, message) {
+  let loc = getLineInfo(this.input, pos)
+  message += " (" + loc.line + ":" + loc.column + ")"
+  let err = new SyntaxError(message)
+  err.pos = pos; err.loc = loc; err.raisedAt = this.pos
+  throw err
+}
+
+pp.raiseRecoverable = pp.raise
+
+pp.curPosition = function() {
+  if (this.options.locations) {
+    return new Position(this.curLine, this.pos - this.lineStart)
+  }
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/locutil.js b/tools/tests/apps/modules/imports/links/acorn/src/locutil.js
new file mode 100644
index 0000000000..5a9465e017
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/locutil.js
@@ -0,0 +1,42 @@
+import {lineBreakG} from "./whitespace"
+
+// These are used when `options.locations` is on, for the
+// `startLoc` and `endLoc` properties.
+
+export class Position {
+  constructor(line, col) {
+    this.line = line
+    this.column = col
+  }
+
+  offset(n) {
+    return new Position(this.line, this.column + n)
+  }
+}
+
+export class SourceLocation {
+  constructor(p, start, end) {
+    this.start = start
+    this.end = end
+    if (p.sourceFile !== null) this.source = p.sourceFile
+  }
+}
+
+// The `getLineInfo` function is mostly useful when the
+// `locations` option is off (for performance reasons) and you
+// want to find the line/column position for a given character
+// offset. `input` should be the code string that the offset refers
+// into.
+
+export function getLineInfo(input, offset) {
+  for (let line = 1, cur = 0;;) {
+    lineBreakG.lastIndex = cur
+    let match = lineBreakG.exec(input)
+    if (match && match.index < offset) {
+      ++line
+      cur = match.index + match[0].length
+    } else {
+      return new Position(line, offset - cur)
+    }
+  }
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/loose/expression.js b/tools/tests/apps/modules/imports/links/acorn/src/loose/expression.js
new file mode 100644
index 0000000000..b6c5ddbcb2
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/loose/expression.js
@@ -0,0 +1,582 @@
+import {LooseParser} from "./state"
+import {isDummy} from "./parseutil"
+import {tokTypes as tt} from "../index"
+
+const lp = LooseParser.prototype
+
+lp.checkLVal = function(expr) {
+  if (!expr) return expr
+  switch (expr.type) {
+  case "Identifier":
+  case "MemberExpression":
+    return expr
+
+  case "ParenthesizedExpression":
+    expr.expression = this.checkLVal(expr.expression)
+    return expr
+
+  default:
+    return this.dummyIdent()
+  }
+}
+
+lp.parseExpression = function(noIn) {
+  let start = this.storeCurrentPos()
+  let expr = this.parseMaybeAssign(noIn)
+  if (this.tok.type === tt.comma) {
+    let node = this.startNodeAt(start)
+    node.expressions = [expr]
+    while (this.eat(tt.comma)) node.expressions.push(this.parseMaybeAssign(noIn))
+    return this.finishNode(node, "SequenceExpression")
+  }
+  return expr
+}
+
+lp.parseParenExpression = function() {
+  this.pushCx()
+  this.expect(tt.parenL)
+  let val = this.parseExpression()
+  this.popCx()
+  this.expect(tt.parenR)
+  return val
+}
+
+lp.parseMaybeAssign = function(noIn) {
+  if (this.toks.isContextual("yield")) {
+    let node = this.startNode()
+    this.next()
+    if (this.semicolon() || this.canInsertSemicolon() || (this.tok.type != tt.star && !this.tok.type.startsExpr)) {
+      node.delegate = false
+      node.argument = null
+    } else {
+      node.delegate = this.eat(tt.star)
+      node.argument = this.parseMaybeAssign()
+    }
+    return this.finishNode(node, "YieldExpression")
+  }
+
+  let start = this.storeCurrentPos()
+  let left = this.parseMaybeConditional(noIn)
+  if (this.tok.type.isAssign) {
+    let node = this.startNodeAt(start)
+    node.operator = this.tok.value
+    node.left = this.tok.type === tt.eq ? this.toAssignable(left) : this.checkLVal(left)
+    this.next()
+    node.right = this.parseMaybeAssign(noIn)
+    return this.finishNode(node, "AssignmentExpression")
+  }
+  return left
+}
+
+lp.parseMaybeConditional = function(noIn) {
+  let start = this.storeCurrentPos()
+  let expr = this.parseExprOps(noIn)
+  if (this.eat(tt.question)) {
+    let node = this.startNodeAt(start)
+    node.test = expr
+    node.consequent = this.parseMaybeAssign()
+    node.alternate = this.expect(tt.colon) ? this.parseMaybeAssign(noIn) : this.dummyIdent()
+    return this.finishNode(node, "ConditionalExpression")
+  }
+  return expr
+}
+
+lp.parseExprOps = function(noIn) {
+  let start = this.storeCurrentPos()
+  let indent = this.curIndent, line = this.curLineStart
+  return this.parseExprOp(this.parseMaybeUnary(false), start, -1, noIn, indent, line)
+}
+
+lp.parseExprOp = function(left, start, minPrec, noIn, indent, line) {
+  if (this.curLineStart != line && this.curIndent < indent && this.tokenStartsLine()) return left
+  let prec = this.tok.type.binop
+  if (prec != null && (!noIn || this.tok.type !== tt._in)) {
+    if (prec > minPrec) {
+      let node = this.startNodeAt(start)
+      node.left = left
+      node.operator = this.tok.value
+      this.next()
+      if (this.curLineStart != line && this.curIndent < indent && this.tokenStartsLine()) {
+        node.right = this.dummyIdent()
+      } else {
+        let rightStart = this.storeCurrentPos()
+        node.right = this.parseExprOp(this.parseMaybeUnary(false), rightStart, prec, noIn, indent, line)
+      }
+      this.finishNode(node, /&&|\|\|/.test(node.operator) ? "LogicalExpression" : "BinaryExpression")
+      return this.parseExprOp(node, start, minPrec, noIn, indent, line)
+    }
+  }
+  return left
+}
+
+lp.parseMaybeUnary = function(sawUnary) {
+  let start = this.storeCurrentPos(), expr
+  if (this.options.ecmaVersion >= 8 && this.inAsync && this.toks.isContextual("await")) {
+    expr = this.parseAwait()
+    sawUnary = true
+  } else if (this.tok.type.prefix) {
+    let node = this.startNode(), update = this.tok.type === tt.incDec
+    if (!update) sawUnary = true
+    node.operator = this.tok.value
+    node.prefix = true
+    this.next()
+    node.argument = this.parseMaybeUnary(true)
+    if (update) node.argument = this.checkLVal(node.argument)
+    expr = this.finishNode(node, update ? "UpdateExpression" : "UnaryExpression")
+  } else if (this.tok.type === tt.ellipsis) {
+    let node = this.startNode()
+    this.next()
+    node.argument = this.parseMaybeUnary(sawUnary)
+    expr = this.finishNode(node, "SpreadElement")
+  } else {
+    expr = this.parseExprSubscripts()
+    while (this.tok.type.postfix && !this.canInsertSemicolon()) {
+      let node = this.startNodeAt(start)
+      node.operator = this.tok.value
+      node.prefix = false
+      node.argument = this.checkLVal(expr)
+      this.next()
+      expr = this.finishNode(node, "UpdateExpression")
+    }
+  }
+
+  if (!sawUnary && this.eat(tt.starstar)) {
+    let node = this.startNodeAt(start)
+    node.operator = "**"
+    node.left = expr
+    node.right = this.parseMaybeUnary(false)
+    return this.finishNode(node, "BinaryExpression")
+  }
+
+  return expr
+}
+
+lp.parseExprSubscripts = function() {
+  let start = this.storeCurrentPos()
+  return this.parseSubscripts(this.parseExprAtom(), start, false, this.curIndent, this.curLineStart)
+}
+
+lp.parseSubscripts = function(base, start, noCalls, startIndent, line) {
+  for (;;) {
+    if (this.curLineStart != line && this.curIndent <= startIndent && this.tokenStartsLine()) {
+      if (this.tok.type == tt.dot && this.curIndent == startIndent)
+        --startIndent
+      else
+        return base
+    }
+
+    let maybeAsyncArrow = base.type === "Identifier" && base.name === "async" && !this.canInsertSemicolon()
+
+    if (this.eat(tt.dot)) {
+      let node = this.startNodeAt(start)
+      node.object = base
+      if (this.curLineStart != line && this.curIndent <= startIndent && this.tokenStartsLine())
+        node.property = this.dummyIdent()
+      else
+        node.property = this.parsePropertyAccessor() || this.dummyIdent()
+      node.computed = false
+      base = this.finishNode(node, "MemberExpression")
+    } else if (this.tok.type == tt.bracketL) {
+      this.pushCx()
+      this.next()
+      let node = this.startNodeAt(start)
+      node.object = base
+      node.property = this.parseExpression()
+      node.computed = true
+      this.popCx()
+      this.expect(tt.bracketR)
+      base = this.finishNode(node, "MemberExpression")
+    } else if (!noCalls && this.tok.type == tt.parenL) {
+      let exprList = this.parseExprList(tt.parenR)
+      if (maybeAsyncArrow && this.eat(tt.arrow))
+        return this.parseArrowExpression(this.startNodeAt(start), exprList, true)
+      let node = this.startNodeAt(start)
+      node.callee = base
+      node.arguments = exprList
+      base = this.finishNode(node, "CallExpression")
+    } else if (this.tok.type == tt.backQuote) {
+      let node = this.startNodeAt(start)
+      node.tag = base
+      node.quasi = this.parseTemplate()
+      base = this.finishNode(node, "TaggedTemplateExpression")
+    } else {
+      return base
+    }
+  }
+}
+
+lp.parseExprAtom = function() {
+  let node
+  switch (this.tok.type) {
+  case tt._this:
+  case tt._super:
+    let type = this.tok.type === tt._this ? "ThisExpression" : "Super"
+    node = this.startNode()
+    this.next()
+    return this.finishNode(node, type)
+
+  case tt.name:
+    let start = this.storeCurrentPos()
+    let id = this.parseIdent()
+    let isAsync = false
+    if (id.name === "async" && !this.canInsertSemicolon()) {
+      if (this.eat(tt._function))
+        return this.parseFunction(this.startNodeAt(start), false, true)
+      if (this.tok.type === tt.name) {
+        id = this.parseIdent()
+        isAsync = true
+      }
+    }
+    return this.eat(tt.arrow) ? this.parseArrowExpression(this.startNodeAt(start), [id], isAsync) : id
+
+  case tt.regexp:
+    node = this.startNode()
+    let val = this.tok.value
+    node.regex = {pattern: val.pattern, flags: val.flags}
+    node.value = val.value
+    node.raw = this.input.slice(this.tok.start, this.tok.end)
+    this.next()
+    return this.finishNode(node, "Literal")
+
+  case tt.num: case tt.string:
+    node = this.startNode()
+    node.value = this.tok.value
+    node.raw = this.input.slice(this.tok.start, this.tok.end)
+    this.next()
+    return this.finishNode(node, "Literal")
+
+  case tt._null: case tt._true: case tt._false:
+    node = this.startNode()
+    node.value = this.tok.type === tt._null ? null : this.tok.type === tt._true
+    node.raw = this.tok.type.keyword
+    this.next()
+    return this.finishNode(node, "Literal")
+
+  case tt.parenL:
+    let parenStart = this.storeCurrentPos()
+    this.next()
+    let inner = this.parseExpression()
+    this.expect(tt.parenR)
+    if (this.eat(tt.arrow)) {
+      // (a,)=>a // SequenceExpression makes dummy in the last hole. Drop the dummy.
+      let params = inner.expressions || [inner]
+      if (params.length && isDummy(params[params.length - 1]))
+        params.pop()
+      return this.parseArrowExpression(this.startNodeAt(parenStart), params)
+    }
+    if (this.options.preserveParens) {
+      let par = this.startNodeAt(parenStart)
+      par.expression = inner
+      inner = this.finishNode(par, "ParenthesizedExpression")
+    }
+    return inner
+
+  case tt.bracketL:
+    node = this.startNode()
+    node.elements = this.parseExprList(tt.bracketR, true)
+    return this.finishNode(node, "ArrayExpression")
+
+  case tt.braceL:
+    return this.parseObj()
+
+  case tt._class:
+    return this.parseClass(false)
+
+  case tt._function:
+    node = this.startNode()
+    this.next()
+    return this.parseFunction(node, false)
+
+  case tt._new:
+    return this.parseNew()
+
+  case tt.backQuote:
+    return this.parseTemplate()
+
+  default:
+    return this.dummyIdent()
+  }
+}
+
+lp.parseNew = function() {
+  let node = this.startNode(), startIndent = this.curIndent, line = this.curLineStart
+  let meta = this.parseIdent(true)
+  if (this.options.ecmaVersion >= 6 && this.eat(tt.dot)) {
+    node.meta = meta
+    node.property = this.parseIdent(true)
+    return this.finishNode(node, "MetaProperty")
+  }
+  let start = this.storeCurrentPos()
+  node.callee = this.parseSubscripts(this.parseExprAtom(), start, true, startIndent, line)
+  if (this.tok.type == tt.parenL) {
+    node.arguments = this.parseExprList(tt.parenR)
+  } else {
+    node.arguments = []
+  }
+  return this.finishNode(node, "NewExpression")
+}
+
+lp.parseTemplateElement = function() {
+  let elem = this.startNode()
+
+  // The loose parser accepts invalid unicode escapes even in untagged templates.
+  if (this.tok.type === tt.invalidTemplate) {
+    elem.value = {
+      raw: this.tok.value,
+      cooked: null
+    }
+  } else {
+    elem.value = {
+      raw: this.input.slice(this.tok.start, this.tok.end).replace(/\r\n?/g, "\n"),
+      cooked: this.tok.value
+    }
+  }
+  this.next()
+  elem.tail = this.tok.type === tt.backQuote
+  return this.finishNode(elem, "TemplateElement")
+}
+
+lp.parseTemplate = function() {
+  let node = this.startNode()
+  this.next()
+  node.expressions = []
+  let curElt = this.parseTemplateElement()
+  node.quasis = [curElt]
+  while (!curElt.tail) {
+    this.next()
+    node.expressions.push(this.parseExpression())
+    if (this.expect(tt.braceR)) {
+      curElt = this.parseTemplateElement()
+    } else {
+      curElt = this.startNode()
+      curElt.value = {cooked: "", raw: ""}
+      curElt.tail = true
+      this.finishNode(curElt, "TemplateElement")
+    }
+    node.quasis.push(curElt)
+  }
+  this.expect(tt.backQuote)
+  return this.finishNode(node, "TemplateLiteral")
+}
+
+lp.parseObj = function() {
+  let node = this.startNode()
+  node.properties = []
+  this.pushCx()
+  let indent = this.curIndent + 1, line = this.curLineStart
+  this.eat(tt.braceL)
+  if (this.curIndent + 1 < indent) { indent = this.curIndent; line = this.curLineStart }
+  while (!this.closes(tt.braceR, indent, line)) {
+    let prop = this.startNode(), isGenerator, isAsync, start
+    if (this.options.ecmaVersion >= 9 && this.eat(tt.ellipsis)) {
+      prop.argument = this.parseMaybeAssign()
+      node.properties.push(this.finishNode(prop, "SpreadElement"))
+      this.eat(tt.comma)
+      continue
+    }
+    if (this.options.ecmaVersion >= 6) {
+      start = this.storeCurrentPos()
+      prop.method = false
+      prop.shorthand = false
+      isGenerator = this.eat(tt.star)
+    }
+    this.parsePropertyName(prop)
+    if (this.toks.isAsyncProp(prop)) {
+      isAsync = true
+      isGenerator = this.options.ecmaVersion >= 9 && this.eat(tt.star)
+      this.parsePropertyName(prop)
+    } else {
+      isAsync = false
+    }
+    if (isDummy(prop.key)) { if (isDummy(this.parseMaybeAssign())) this.next(); this.eat(tt.comma); continue }
+    if (this.eat(tt.colon)) {
+      prop.kind = "init"
+      prop.value = this.parseMaybeAssign()
+    } else if (this.options.ecmaVersion >= 6 && (this.tok.type === tt.parenL || this.tok.type === tt.braceL)) {
+      prop.kind = "init"
+      prop.method = true
+      prop.value = this.parseMethod(isGenerator, isAsync)
+    } else if (this.options.ecmaVersion >= 5 && prop.key.type === "Identifier" &&
+               !prop.computed && (prop.key.name === "get" || prop.key.name === "set") &&
+               (this.tok.type != tt.comma && this.tok.type != tt.braceR && this.tok.type != tt.eq)) {
+      prop.kind = prop.key.name
+      this.parsePropertyName(prop)
+      prop.value = this.parseMethod(false)
+    } else {
+      prop.kind = "init"
+      if (this.options.ecmaVersion >= 6) {
+        if (this.eat(tt.eq)) {
+          let assign = this.startNodeAt(start)
+          assign.operator = "="
+          assign.left = prop.key
+          assign.right = this.parseMaybeAssign()
+          prop.value = this.finishNode(assign, "AssignmentExpression")
+        } else {
+          prop.value = prop.key
+        }
+      } else {
+        prop.value = this.dummyIdent()
+      }
+      prop.shorthand = true
+    }
+    node.properties.push(this.finishNode(prop, "Property"))
+    this.eat(tt.comma)
+  }
+  this.popCx()
+  if (!this.eat(tt.braceR)) {
+    // If there is no closing brace, make the node span to the start
+    // of the next token (this is useful for Tern)
+    this.last.end = this.tok.start
+    if (this.options.locations) this.last.loc.end = this.tok.loc.start
+  }
+  return this.finishNode(node, "ObjectExpression")
+}
+
+lp.parsePropertyName = function(prop) {
+  if (this.options.ecmaVersion >= 6) {
+    if (this.eat(tt.bracketL)) {
+      prop.computed = true
+      prop.key = this.parseExpression()
+      this.expect(tt.bracketR)
+      return
+    } else {
+      prop.computed = false
+    }
+  }
+  let key = (this.tok.type === tt.num || this.tok.type === tt.string) ? this.parseExprAtom() : this.parseIdent()
+  prop.key = key || this.dummyIdent()
+}
+
+lp.parsePropertyAccessor = function() {
+  if (this.tok.type === tt.name || this.tok.type.keyword) return this.parseIdent()
+}
+
+lp.parseIdent = function() {
+  let name = this.tok.type === tt.name ? this.tok.value : this.tok.type.keyword
+  if (!name) return this.dummyIdent()
+  let node = this.startNode()
+  this.next()
+  node.name = name
+  return this.finishNode(node, "Identifier")
+}
+
+lp.initFunction = function(node) {
+  node.id = null
+  node.params = []
+  if (this.options.ecmaVersion >= 6) {
+    node.generator = false
+    node.expression = false
+  }
+  if (this.options.ecmaVersion >= 8)
+    node.async = false
+}
+
+// Convert existing expression atom to assignable pattern
+// if possible.
+
+lp.toAssignable = function(node, binding) {
+  if (!node || node.type == "Identifier" || (node.type == "MemberExpression" && !binding)) {
+    // Okay
+  } else if (node.type == "ParenthesizedExpression") {
+    this.toAssignable(node.expression, binding)
+  } else if (this.options.ecmaVersion < 6) {
+    return this.dummyIdent()
+  } else if (node.type == "ObjectExpression") {
+    node.type = "ObjectPattern"
+    for (let prop of node.properties)
+      this.toAssignable(prop, binding)
+  } else if (node.type == "ArrayExpression") {
+    node.type = "ArrayPattern"
+    this.toAssignableList(node.elements, binding)
+  } else if (node.type == "Property") {
+    this.toAssignable(node.value, binding)
+  } else if (node.type == "SpreadElement") {
+    node.type = "RestElement"
+    this.toAssignable(node.argument, binding)
+  } else if (node.type == "AssignmentExpression") {
+    node.type = "AssignmentPattern"
+    delete node.operator
+  } else {
+    return this.dummyIdent()
+  }
+  return node
+}
+
+lp.toAssignableList = function(exprList, binding) {
+  for (let expr of exprList)
+    this.toAssignable(expr, binding)
+  return exprList
+}
+
+lp.parseFunctionParams = function(params) {
+  params = this.parseExprList(tt.parenR)
+  return this.toAssignableList(params, true)
+}
+
+lp.parseMethod = function(isGenerator, isAsync) {
+  let node = this.startNode(), oldInAsync = this.inAsync
+  this.initFunction(node)
+  if (this.options.ecmaVersion >= 6)
+    node.generator = !!isGenerator
+  if (this.options.ecmaVersion >= 8)
+    node.async = !!isAsync
+  this.inAsync = node.async
+  node.params = this.parseFunctionParams()
+  node.body = this.parseBlock()
+  this.toks.adaptDirectivePrologue(node.body.body)
+  this.inAsync = oldInAsync
+  return this.finishNode(node, "FunctionExpression")
+}
+
+lp.parseArrowExpression = function(node, params, isAsync) {
+  let oldInAsync = this.inAsync
+  this.initFunction(node)
+  if (this.options.ecmaVersion >= 8)
+    node.async = !!isAsync
+  this.inAsync = node.async
+  node.params = this.toAssignableList(params, true)
+  node.expression = this.tok.type !== tt.braceL
+  if (node.expression) {
+    node.body = this.parseMaybeAssign()
+  } else {
+    node.body = this.parseBlock()
+    this.toks.adaptDirectivePrologue(node.body.body)
+  }
+  this.inAsync = oldInAsync
+  return this.finishNode(node, "ArrowFunctionExpression")
+}
+
+lp.parseExprList = function(close, allowEmpty) {
+  this.pushCx()
+  let indent = this.curIndent, line = this.curLineStart, elts = []
+  this.next() // Opening bracket
+  while (!this.closes(close, indent + 1, line)) {
+    if (this.eat(tt.comma)) {
+      elts.push(allowEmpty ? null : this.dummyIdent())
+      continue
+    }
+    let elt = this.parseMaybeAssign()
+    if (isDummy(elt)) {
+      if (this.closes(close, indent, line)) break
+      this.next()
+    } else {
+      elts.push(elt)
+    }
+    this.eat(tt.comma)
+  }
+  this.popCx()
+  if (!this.eat(close)) {
+    // If there is no closing brace, make the node span to the start
+    // of the next token (this is useful for Tern)
+    this.last.end = this.tok.start
+    if (this.options.locations) this.last.loc.end = this.tok.loc.start
+  }
+  return elts
+}
+
+lp.parseAwait = function() {
+  let node = this.startNode()
+  this.next()
+  node.argument = this.parseMaybeUnary()
+  return this.finishNode(node, "AwaitExpression")
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/loose/index.js b/tools/tests/apps/modules/imports/links/acorn/src/loose/index.js
new file mode 100644
index 0000000000..a698061a8b
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/loose/index.js
@@ -0,0 +1,47 @@
+// Acorn: Loose parser
+//
+// This module provides an alternative parser (`parse_dammit`) that
+// exposes that same interface as `parse`, but will try to parse
+// anything as JavaScript, repairing syntax error the best it can.
+// There are circumstances in which it will raise an error and give
+// up, but they are very rare. The resulting AST will be a mostly
+// valid JavaScript AST (as per the [Mozilla parser API][api], except
+// that:
+//
+// - Return outside functions is allowed
+//
+// - Label consistency (no conflicts, break only to existing labels)
+//   is not enforced.
+//
+// - Bogus Identifier nodes with a name of `"✖"` are inserted whenever
+//   the parser got too confused to return anything meaningful.
+//
+// [api]: https://developer.mozilla.org/en-US/docs/SpiderMonkey/Parser_API
+//
+// The expected use for this is to *first* try `acorn.parse`, and only
+// if that fails switch to `parse_dammit`. The loose parser might
+// parse badly indented code incorrectly, so **don't** use it as
+// your default parser.
+//
+// Quite a lot of acorn.js is duplicated here. The alternative was to
+// add a *lot* of extra cruft to that file, making it less readable
+// and slower. Copying and editing the code allowed me to make
+// invasive changes and simplifications without creating a complicated
+// tangle.
+
+import {addLooseExports, defaultOptions} from "../index"
+import {LooseParser, pluginsLoose} from "./state"
+import "./tokenize"
+import "./statement"
+import "./expression"
+
+export {LooseParser, pluginsLoose} from "./state"
+
+defaultOptions.tabSize = 4
+
+// eslint-disable-next-line camelcase
+export function parse_dammit(input, options) {
+  return new LooseParser(input, options).parse()
+}
+
+addLooseExports(parse_dammit, LooseParser, pluginsLoose)
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/loose/parseutil.js b/tools/tests/apps/modules/imports/links/acorn/src/loose/parseutil.js
new file mode 100644
index 0000000000..b620fdaf0a
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/loose/parseutil.js
@@ -0,0 +1 @@
+export function isDummy(node) { return node.name == "✖" }
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/loose/state.js b/tools/tests/apps/modules/imports/links/acorn/src/loose/state.js
new file mode 100644
index 0000000000..da068edb51
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/loose/state.js
@@ -0,0 +1,170 @@
+import {tokenizer, SourceLocation, tokTypes as tt, Node, lineBreak, isNewLine} from "../index"
+
+function noop() {}
+
+// Registered plugins
+export const pluginsLoose = {}
+
+export class LooseParser {
+  constructor(input, options = {}) {
+    this.toks = tokenizer(input, options)
+    this.options = this.toks.options
+    this.input = this.toks.input
+    this.tok = this.last = {type: tt.eof, start: 0, end: 0}
+    this.tok.validateRegExpFlags = noop
+    this.tok.validateRegExpPattern = noop
+    if (this.options.locations) {
+      let here = this.toks.curPosition()
+      this.tok.loc = new SourceLocation(this.toks, here, here)
+    }
+    this.ahead = [] // Tokens ahead
+    this.context = [] // Indentation contexted
+    this.curIndent = 0
+    this.curLineStart = 0
+    this.nextLineStart = this.lineEnd(this.curLineStart) + 1
+    this.inAsync = false
+    // Load plugins
+    this.options.pluginsLoose = options.pluginsLoose || {}
+    this.loadPlugins(this.options.pluginsLoose)
+  }
+
+  startNode() {
+    return new Node(this.toks, this.tok.start, this.options.locations ? this.tok.loc.start : null)
+  }
+
+  storeCurrentPos() {
+    return this.options.locations ? [this.tok.start, this.tok.loc.start] : this.tok.start
+  }
+
+  startNodeAt(pos) {
+    if (this.options.locations) {
+      return new Node(this.toks, pos[0], pos[1])
+    } else {
+      return new Node(this.toks, pos)
+    }
+  }
+
+  finishNode(node, type) {
+    node.type = type
+    node.end = this.last.end
+    if (this.options.locations)
+      node.loc.end = this.last.loc.end
+    if (this.options.ranges)
+      node.range[1] = this.last.end
+    return node
+  }
+
+  dummyNode(type) {
+    let dummy = this.startNode()
+    dummy.type = type
+    dummy.end = dummy.start
+    if (this.options.locations)
+      dummy.loc.end = dummy.loc.start
+    if (this.options.ranges)
+      dummy.range[1] = dummy.start
+    this.last = {type: tt.name, start: dummy.start, end: dummy.start, loc: dummy.loc}
+    return dummy
+  }
+
+  dummyIdent() {
+    let dummy = this.dummyNode("Identifier")
+    dummy.name = "✖"
+    return dummy
+  }
+
+  dummyString() {
+    let dummy = this.dummyNode("Literal")
+    dummy.value = dummy.raw = "✖"
+    return dummy
+  }
+
+  eat(type) {
+    if (this.tok.type === type) {
+      this.next()
+      return true
+    } else {
+      return false
+    }
+  }
+
+  isContextual(name) {
+    return this.tok.type === tt.name && this.tok.value === name
+  }
+
+  eatContextual(name) {
+    return this.tok.value === name && this.eat(tt.name)
+  }
+
+  canInsertSemicolon() {
+    return this.tok.type === tt.eof || this.tok.type === tt.braceR ||
+      lineBreak.test(this.input.slice(this.last.end, this.tok.start))
+  }
+
+  semicolon() {
+    return this.eat(tt.semi)
+  }
+
+  expect(type) {
+    if (this.eat(type)) return true
+    for (let i = 1; i <= 2; i++) {
+      if (this.lookAhead(i).type == type) {
+        for (let j = 0; j < i; j++) this.next()
+        return true
+      }
+    }
+  }
+
+  pushCx() {
+    this.context.push(this.curIndent)
+  }
+
+  popCx() {
+    this.curIndent = this.context.pop()
+  }
+
+  lineEnd(pos) {
+    while (pos < this.input.length && !isNewLine(this.input.charCodeAt(pos))) ++pos
+    return pos
+  }
+
+  indentationAfter(pos) {
+    for (let count = 0;; ++pos) {
+      let ch = this.input.charCodeAt(pos)
+      if (ch === 32) ++count
+      else if (ch === 9) count += this.options.tabSize
+      else return count
+    }
+  }
+
+  closes(closeTok, indent, line, blockHeuristic) {
+    if (this.tok.type === closeTok || this.tok.type === tt.eof) return true
+    return line != this.curLineStart && this.curIndent < indent && this.tokenStartsLine() &&
+      (!blockHeuristic || this.nextLineStart >= this.input.length ||
+       this.indentationAfter(this.nextLineStart) < indent)
+  }
+
+  tokenStartsLine() {
+    for (let p = this.tok.start - 1; p >= this.curLineStart; --p) {
+      let ch = this.input.charCodeAt(p)
+      if (ch !== 9 && ch !== 32) return false
+    }
+    return true
+  }
+
+  extend(name, f) {
+    this[name] = f(this[name])
+  }
+
+  loadPlugins(pluginConfigs) {
+    for (let name in pluginConfigs) {
+      let plugin = pluginsLoose[name]
+      if (!plugin) throw new Error("Plugin '" + name + "' not found")
+      plugin(this, pluginConfigs[name])
+    }
+  }
+
+  parse() {
+    this.next()
+    return this.parseTopLevel()
+  }
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/loose/statement.js b/tools/tests/apps/modules/imports/links/acorn/src/loose/statement.js
new file mode 100644
index 0000000000..aa30696c41
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/loose/statement.js
@@ -0,0 +1,459 @@
+import {LooseParser} from "./state"
+import {isDummy} from "./parseutil"
+import {getLineInfo, tokTypes as tt} from "../index"
+
+const lp = LooseParser.prototype
+
+lp.parseTopLevel = function() {
+  let node = this.startNodeAt(this.options.locations ? [0, getLineInfo(this.input, 0)] : 0)
+  node.body = []
+  while (this.tok.type !== tt.eof) node.body.push(this.parseStatement())
+  this.toks.adaptDirectivePrologue(node.body)
+  this.last = this.tok
+  if (this.options.ecmaVersion >= 6) {
+    node.sourceType = this.options.sourceType
+  }
+  return this.finishNode(node, "Program")
+}
+
+lp.parseStatement = function() {
+  let starttype = this.tok.type, node = this.startNode(), kind
+
+  if (this.toks.isLet()) {
+    starttype = tt._var
+    kind = "let"
+  }
+
+  switch (starttype) {
+  case tt._break: case tt._continue:
+    this.next()
+    let isBreak = starttype === tt._break
+    if (this.semicolon() || this.canInsertSemicolon()) {
+      node.label = null
+    } else {
+      node.label = this.tok.type === tt.name ? this.parseIdent() : null
+      this.semicolon()
+    }
+    return this.finishNode(node, isBreak ? "BreakStatement" : "ContinueStatement")
+
+  case tt._debugger:
+    this.next()
+    this.semicolon()
+    return this.finishNode(node, "DebuggerStatement")
+
+  case tt._do:
+    this.next()
+    node.body = this.parseStatement()
+    node.test = this.eat(tt._while) ? this.parseParenExpression() : this.dummyIdent()
+    this.semicolon()
+    return this.finishNode(node, "DoWhileStatement")
+
+  case tt._for:
+    this.next() // `for` keyword
+    let isAwait = this.options.ecmaVersion >= 9 && this.inAsync && this.eatContextual("await")
+
+    this.pushCx()
+    this.expect(tt.parenL)
+    if (this.tok.type === tt.semi) return this.parseFor(node, null)
+    let isLet = this.toks.isLet()
+    if (isLet || this.tok.type === tt._var || this.tok.type === tt._const) {
+      let init = this.parseVar(true, isLet ? "let" : this.tok.value)
+      if (init.declarations.length === 1 && (this.tok.type === tt._in || this.isContextual("of"))) {
+        if (this.options.ecmaVersion >= 9 && this.tok.type !== tt._in) {
+          node.await = isAwait
+        }
+        return this.parseForIn(node, init)
+      }
+      return this.parseFor(node, init)
+    }
+    let init = this.parseExpression(true)
+    if (this.tok.type === tt._in || this.isContextual("of")) {
+      if (this.options.ecmaVersion >= 9 && this.tok.type !== tt._in) {
+        node.await = isAwait
+      }
+      return this.parseForIn(node, this.toAssignable(init))
+    }
+    return this.parseFor(node, init)
+
+  case tt._function:
+    this.next()
+    return this.parseFunction(node, true)
+
+  case tt._if:
+    this.next()
+    node.test = this.parseParenExpression()
+    node.consequent = this.parseStatement()
+    node.alternate = this.eat(tt._else) ? this.parseStatement() : null
+    return this.finishNode(node, "IfStatement")
+
+  case tt._return:
+    this.next()
+    if (this.eat(tt.semi) || this.canInsertSemicolon()) node.argument = null
+    else { node.argument = this.parseExpression(); this.semicolon() }
+    return this.finishNode(node, "ReturnStatement")
+
+  case tt._switch:
+    let blockIndent = this.curIndent, line = this.curLineStart
+    this.next()
+    node.discriminant = this.parseParenExpression()
+    node.cases = []
+    this.pushCx()
+    this.expect(tt.braceL)
+
+    let cur
+    while (!this.closes(tt.braceR, blockIndent, line, true)) {
+      if (this.tok.type === tt._case || this.tok.type === tt._default) {
+        let isCase = this.tok.type === tt._case
+        if (cur) this.finishNode(cur, "SwitchCase")
+        node.cases.push(cur = this.startNode())
+        cur.consequent = []
+        this.next()
+        if (isCase) cur.test = this.parseExpression()
+        else cur.test = null
+        this.expect(tt.colon)
+      } else {
+        if (!cur) {
+          node.cases.push(cur = this.startNode())
+          cur.consequent = []
+          cur.test = null
+        }
+        cur.consequent.push(this.parseStatement())
+      }
+    }
+    if (cur) this.finishNode(cur, "SwitchCase")
+    this.popCx()
+    this.eat(tt.braceR)
+    return this.finishNode(node, "SwitchStatement")
+
+  case tt._throw:
+    this.next()
+    node.argument = this.parseExpression()
+    this.semicolon()
+    return this.finishNode(node, "ThrowStatement")
+
+  case tt._try:
+    this.next()
+    node.block = this.parseBlock()
+    node.handler = null
+    if (this.tok.type === tt._catch) {
+      let clause = this.startNode()
+      this.next()
+      this.expect(tt.parenL)
+      clause.param = this.toAssignable(this.parseExprAtom(), true)
+      this.expect(tt.parenR)
+      clause.body = this.parseBlock()
+      node.handler = this.finishNode(clause, "CatchClause")
+    }
+    node.finalizer = this.eat(tt._finally) ? this.parseBlock() : null
+    if (!node.handler && !node.finalizer) return node.block
+    return this.finishNode(node, "TryStatement")
+
+  case tt._var:
+  case tt._const:
+    return this.parseVar(false, kind || this.tok.value)
+
+  case tt._while:
+    this.next()
+    node.test = this.parseParenExpression()
+    node.body = this.parseStatement()
+    return this.finishNode(node, "WhileStatement")
+
+  case tt._with:
+    this.next()
+    node.object = this.parseParenExpression()
+    node.body = this.parseStatement()
+    return this.finishNode(node, "WithStatement")
+
+  case tt.braceL:
+    return this.parseBlock()
+
+  case tt.semi:
+    this.next()
+    return this.finishNode(node, "EmptyStatement")
+
+  case tt._class:
+    return this.parseClass(true)
+
+  case tt._import:
+    return this.parseImport()
+
+  case tt._export:
+    return this.parseExport()
+
+  default:
+    if (this.toks.isAsyncFunction()) {
+      this.next()
+      this.next()
+      return this.parseFunction(node, true, true)
+    }
+    let expr = this.parseExpression()
+    if (isDummy(expr)) {
+      this.next()
+      if (this.tok.type === tt.eof) return this.finishNode(node, "EmptyStatement")
+      return this.parseStatement()
+    } else if (starttype === tt.name && expr.type === "Identifier" && this.eat(tt.colon)) {
+      node.body = this.parseStatement()
+      node.label = expr
+      return this.finishNode(node, "LabeledStatement")
+    } else {
+      node.expression = expr
+      this.semicolon()
+      return this.finishNode(node, "ExpressionStatement")
+    }
+  }
+}
+
+lp.parseBlock = function() {
+  let node = this.startNode()
+  this.pushCx()
+  this.expect(tt.braceL)
+  let blockIndent = this.curIndent, line = this.curLineStart
+  node.body = []
+  while (!this.closes(tt.braceR, blockIndent, line, true))
+    node.body.push(this.parseStatement())
+  this.popCx()
+  this.eat(tt.braceR)
+  return this.finishNode(node, "BlockStatement")
+}
+
+lp.parseFor = function(node, init) {
+  node.init = init
+  node.test = node.update = null
+  if (this.eat(tt.semi) && this.tok.type !== tt.semi) node.test = this.parseExpression()
+  if (this.eat(tt.semi) && this.tok.type !== tt.parenR) node.update = this.parseExpression()
+  this.popCx()
+  this.expect(tt.parenR)
+  node.body = this.parseStatement()
+  return this.finishNode(node, "ForStatement")
+}
+
+lp.parseForIn = function(node, init) {
+  let type = this.tok.type === tt._in ? "ForInStatement" : "ForOfStatement"
+  this.next()
+  node.left = init
+  node.right = this.parseExpression()
+  this.popCx()
+  this.expect(tt.parenR)
+  node.body = this.parseStatement()
+  return this.finishNode(node, type)
+}
+
+lp.parseVar = function(noIn, kind) {
+  let node = this.startNode()
+  node.kind = kind
+  this.next()
+  node.declarations = []
+  do {
+    let decl = this.startNode()
+    decl.id = this.options.ecmaVersion >= 6 ? this.toAssignable(this.parseExprAtom(), true) : this.parseIdent()
+    decl.init = this.eat(tt.eq) ? this.parseMaybeAssign(noIn) : null
+    node.declarations.push(this.finishNode(decl, "VariableDeclarator"))
+  } while (this.eat(tt.comma))
+  if (!node.declarations.length) {
+    let decl = this.startNode()
+    decl.id = this.dummyIdent()
+    node.declarations.push(this.finishNode(decl, "VariableDeclarator"))
+  }
+  if (!noIn) this.semicolon()
+  return this.finishNode(node, "VariableDeclaration")
+}
+
+lp.parseClass = function(isStatement) {
+  let node = this.startNode()
+  this.next()
+  if (this.tok.type === tt.name) node.id = this.parseIdent()
+  else if (isStatement === true) node.id = this.dummyIdent()
+  else node.id = null
+  node.superClass = this.eat(tt._extends) ? this.parseExpression() : null
+  node.body = this.startNode()
+  node.body.body = []
+  this.pushCx()
+  let indent = this.curIndent + 1, line = this.curLineStart
+  this.eat(tt.braceL)
+  if (this.curIndent + 1 < indent) { indent = this.curIndent; line = this.curLineStart }
+  while (!this.closes(tt.braceR, indent, line)) {
+    if (this.semicolon()) continue
+    let method = this.startNode(), isGenerator, isAsync
+    if (this.options.ecmaVersion >= 6) {
+      method.static = false
+      isGenerator = this.eat(tt.star)
+    }
+    this.parsePropertyName(method)
+    if (isDummy(method.key)) { if (isDummy(this.parseMaybeAssign())) this.next(); this.eat(tt.comma); continue }
+    if (method.key.type === "Identifier" && !method.computed && method.key.name === "static" &&
+        (this.tok.type != tt.parenL && this.tok.type != tt.braceL)) {
+      method.static = true
+      isGenerator = this.eat(tt.star)
+      this.parsePropertyName(method)
+    } else {
+      method.static = false
+    }
+    if (!method.computed &&
+        method.key.type === "Identifier" && method.key.name === "async" && this.tok.type !== tt.parenL &&
+        !this.canInsertSemicolon()) {
+      isAsync = true
+      isGenerator = this.options.ecmaVersion >= 9 && this.eat(tt.star)
+      this.parsePropertyName(method)
+    } else {
+      isAsync = false
+    }
+    if (this.options.ecmaVersion >= 5 && method.key.type === "Identifier" &&
+        !method.computed && (method.key.name === "get" || method.key.name === "set") &&
+        this.tok.type !== tt.parenL && this.tok.type !== tt.braceL) {
+      method.kind = method.key.name
+      this.parsePropertyName(method)
+      method.value = this.parseMethod(false)
+    } else {
+      if (!method.computed && !method.static && !isGenerator && !isAsync && (
+        method.key.type === "Identifier" && method.key.name === "constructor" ||
+          method.key.type === "Literal" && method.key.value === "constructor")) {
+        method.kind = "constructor"
+      } else {
+        method.kind = "method"
+      }
+      method.value = this.parseMethod(isGenerator, isAsync)
+    }
+    node.body.body.push(this.finishNode(method, "MethodDefinition"))
+  }
+  this.popCx()
+  if (!this.eat(tt.braceR)) {
+    // If there is no closing brace, make the node span to the start
+    // of the next token (this is useful for Tern)
+    this.last.end = this.tok.start
+    if (this.options.locations) this.last.loc.end = this.tok.loc.start
+  }
+  this.semicolon()
+  this.finishNode(node.body, "ClassBody")
+  return this.finishNode(node, isStatement ? "ClassDeclaration" : "ClassExpression")
+}
+
+lp.parseFunction = function(node, isStatement, isAsync) {
+  let oldInAsync = this.inAsync
+  this.initFunction(node)
+  if (this.options.ecmaVersion >= 6) {
+    node.generator = this.eat(tt.star)
+  }
+  if (this.options.ecmaVersion >= 8) {
+    node.async = !!isAsync
+  }
+  if (this.tok.type === tt.name) node.id = this.parseIdent()
+  else if (isStatement === true) node.id = this.dummyIdent()
+  this.inAsync = node.async
+  node.params = this.parseFunctionParams()
+  node.body = this.parseBlock()
+  this.toks.adaptDirectivePrologue(node.body.body)
+  this.inAsync = oldInAsync
+  return this.finishNode(node, isStatement ? "FunctionDeclaration" : "FunctionExpression")
+}
+
+lp.parseExport = function() {
+  let node = this.startNode()
+  this.next()
+  if (this.eat(tt.star)) {
+    node.source = this.eatContextual("from") ? this.parseExprAtom() : this.dummyString()
+    return this.finishNode(node, "ExportAllDeclaration")
+  }
+  if (this.eat(tt._default)) {
+    // export default (function foo() {}) // This is FunctionExpression.
+    let isAsync
+    if (this.tok.type === tt._function || (isAsync = this.toks.isAsyncFunction())) {
+      let fNode = this.startNode()
+      this.next()
+      if (isAsync) this.next()
+      node.declaration = this.parseFunction(fNode, "nullableID", isAsync)
+    } else if (this.tok.type === tt._class) {
+      node.declaration = this.parseClass("nullableID")
+    } else {
+      node.declaration = this.parseMaybeAssign()
+      this.semicolon()
+    }
+    return this.finishNode(node, "ExportDefaultDeclaration")
+  }
+  if (this.tok.type.keyword || this.toks.isLet() || this.toks.isAsyncFunction()) {
+    node.declaration = this.parseStatement()
+    node.specifiers = []
+    node.source = null
+  } else {
+    node.declaration = null
+    node.specifiers = this.parseExportSpecifierList()
+    node.source = this.eatContextual("from") ? this.parseExprAtom() : null
+    this.semicolon()
+  }
+  return this.finishNode(node, "ExportNamedDeclaration")
+}
+
+lp.parseImport = function() {
+  let node = this.startNode()
+  this.next()
+  if (this.tok.type === tt.string) {
+    node.specifiers = []
+    node.source = this.parseExprAtom()
+  } else {
+    let elt
+    if (this.tok.type === tt.name && this.tok.value !== "from") {
+      elt = this.startNode()
+      elt.local = this.parseIdent()
+      this.finishNode(elt, "ImportDefaultSpecifier")
+      this.eat(tt.comma)
+    }
+    node.specifiers = this.parseImportSpecifierList()
+    node.source = this.eatContextual("from") && this.tok.type == tt.string ? this.parseExprAtom() : this.dummyString()
+    if (elt) node.specifiers.unshift(elt)
+  }
+  this.semicolon()
+  return this.finishNode(node, "ImportDeclaration")
+}
+
+lp.parseImportSpecifierList = function() {
+  let elts = []
+  if (this.tok.type === tt.star) {
+    let elt = this.startNode()
+    this.next()
+    elt.local = this.eatContextual("as") ? this.parseIdent() : this.dummyIdent()
+    elts.push(this.finishNode(elt, "ImportNamespaceSpecifier"))
+  } else {
+    let indent = this.curIndent, line = this.curLineStart, continuedLine = this.nextLineStart
+    this.pushCx()
+    this.eat(tt.braceL)
+    if (this.curLineStart > continuedLine) continuedLine = this.curLineStart
+    while (!this.closes(tt.braceR, indent + (this.curLineStart <= continuedLine ? 1 : 0), line)) {
+      let elt = this.startNode()
+      if (this.eat(tt.star)) {
+        elt.local = this.eatContextual("as") ? this.parseIdent() : this.dummyIdent()
+        this.finishNode(elt, "ImportNamespaceSpecifier")
+      } else {
+        if (this.isContextual("from")) break
+        elt.imported = this.parseIdent()
+        if (isDummy(elt.imported)) break
+        elt.local = this.eatContextual("as") ? this.parseIdent() : elt.imported
+        this.finishNode(elt, "ImportSpecifier")
+      }
+      elts.push(elt)
+      this.eat(tt.comma)
+    }
+    this.eat(tt.braceR)
+    this.popCx()
+  }
+  return elts
+}
+
+lp.parseExportSpecifierList = function() {
+  let elts = []
+  let indent = this.curIndent, line = this.curLineStart, continuedLine = this.nextLineStart
+  this.pushCx()
+  this.eat(tt.braceL)
+  if (this.curLineStart > continuedLine) continuedLine = this.curLineStart
+  while (!this.closes(tt.braceR, indent + (this.curLineStart <= continuedLine ? 1 : 0), line)) {
+    if (this.isContextual("from")) break
+    let elt = this.startNode()
+    elt.local = this.parseIdent()
+    if (isDummy(elt.local)) break
+    elt.exported = this.eatContextual("as") ? this.parseIdent() : elt.local
+    this.finishNode(elt, "ExportSpecifier")
+    elts.push(elt)
+    this.eat(tt.comma)
+  }
+  this.eat(tt.braceR)
+  this.popCx()
+  return elts
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/loose/tokenize.js b/tools/tests/apps/modules/imports/links/acorn/src/loose/tokenize.js
new file mode 100644
index 0000000000..619b6ee9e4
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/loose/tokenize.js
@@ -0,0 +1,111 @@
+import {tokTypes as tt, Token, isNewLine, SourceLocation, getLineInfo, lineBreakG} from "../index"
+import {LooseParser} from "./state"
+
+const lp = LooseParser.prototype
+
+function isSpace(ch) {
+  return (ch < 14 && ch > 8) || ch === 32 || ch === 160 || isNewLine(ch)
+}
+
+lp.next = function() {
+  this.last = this.tok
+  if (this.ahead.length)
+    this.tok = this.ahead.shift()
+  else
+    this.tok = this.readToken()
+
+  if (this.tok.start >= this.nextLineStart) {
+    while (this.tok.start >= this.nextLineStart) {
+      this.curLineStart = this.nextLineStart
+      this.nextLineStart = this.lineEnd(this.curLineStart) + 1
+    }
+    this.curIndent = this.indentationAfter(this.curLineStart)
+  }
+}
+
+lp.readToken = function() {
+  for (;;) {
+    try {
+      this.toks.next()
+      if (this.toks.type === tt.dot &&
+          this.input.substr(this.toks.end, 1) === "." &&
+          this.options.ecmaVersion >= 6) {
+        this.toks.end++
+        this.toks.type = tt.ellipsis
+      }
+      return new Token(this.toks)
+    } catch (e) {
+      if (!(e instanceof SyntaxError)) throw e
+
+      // Try to skip some text, based on the error message, and then continue
+      let msg = e.message, pos = e.raisedAt, replace = true
+      if (/unterminated/i.test(msg)) {
+        pos = this.lineEnd(e.pos + 1)
+        if (/string/.test(msg)) {
+          replace = {start: e.pos, end: pos, type: tt.string, value: this.input.slice(e.pos + 1, pos)}
+        } else if (/regular expr/i.test(msg)) {
+          let re = this.input.slice(e.pos, pos)
+          try { re = new RegExp(re) } catch (e) { /* ignore compilation error due to new syntax */ }
+          replace = {start: e.pos, end: pos, type: tt.regexp, value: re}
+        } else if (/template/.test(msg)) {
+          replace = {
+            start: e.pos,
+            end: pos,
+            type: tt.template,
+            value: this.input.slice(e.pos, pos)
+          }
+        } else {
+          replace = false
+        }
+      } else if (/invalid (unicode|regexp|number)|expecting unicode|octal literal|is reserved|directly after number|expected number in radix/i.test(msg)) {
+        while (pos < this.input.length && !isSpace(this.input.charCodeAt(pos))) ++pos
+      } else if (/character escape|expected hexadecimal/i.test(msg)) {
+        while (pos < this.input.length) {
+          let ch = this.input.charCodeAt(pos++)
+          if (ch === 34 || ch === 39 || isNewLine(ch)) break
+        }
+      } else if (/unexpected character/i.test(msg)) {
+        pos++
+        replace = false
+      } else if (/regular expression/i.test(msg)) {
+        replace = true
+      } else {
+        throw e
+      }
+      this.resetTo(pos)
+      if (replace === true) replace = {start: pos, end: pos, type: tt.name, value: "✖"}
+      if (replace) {
+        if (this.options.locations)
+          replace.loc = new SourceLocation(
+            this.toks,
+            getLineInfo(this.input, replace.start),
+            getLineInfo(this.input, replace.end))
+        return replace
+      }
+    }
+  }
+}
+
+lp.resetTo = function(pos) {
+  this.toks.pos = pos
+  let ch = this.input.charAt(pos - 1)
+  this.toks.exprAllowed = !ch || /[[{(,;:?/*=+\-~!|&%^<>]/.test(ch) ||
+    /[enwfd]/.test(ch) &&
+    /\b(case|else|return|throw|new|in|(instance|type)?of|delete|void)$/.test(this.input.slice(pos - 10, pos))
+
+  if (this.options.locations) {
+    this.toks.curLine = 1
+    this.toks.lineStart = lineBreakG.lastIndex = 0
+    let match
+    while ((match = lineBreakG.exec(this.input)) && match.index < pos) {
+      ++this.toks.curLine
+      this.toks.lineStart = match.index + match[0].length
+    }
+  }
+}
+
+lp.lookAhead = function(n) {
+  while (n > this.ahead.length)
+    this.ahead.push(this.readToken())
+  return this.ahead[n - 1]
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/lval.js b/tools/tests/apps/modules/imports/links/acorn/src/lval.js
new file mode 100644
index 0000000000..0fc1bc5284
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/lval.js
@@ -0,0 +1,248 @@
+import {types as tt} from "./tokentype"
+import {Parser} from "./state"
+import {has} from "./util"
+
+const pp = Parser.prototype
+
+// Convert existing expression atom to assignable pattern
+// if possible.
+
+pp.toAssignable = function(node, isBinding, refDestructuringErrors) {
+  if (this.options.ecmaVersion >= 6 && node) {
+    switch (node.type) {
+    case "Identifier":
+      if (this.inAsync && node.name === "await")
+        this.raise(node.start, "Can not use 'await' as identifier inside an async function")
+      break
+
+    case "ObjectPattern":
+    case "ArrayPattern":
+    case "RestElement":
+      break
+
+    case "ObjectExpression":
+      node.type = "ObjectPattern"
+      if (refDestructuringErrors) this.checkPatternErrors(refDestructuringErrors, true)
+      for (let prop of node.properties) {
+        this.toAssignable(prop, isBinding)
+        // Early error:
+        //   AssignmentRestProperty[Yield, Await] :
+        //     `...` DestructuringAssignmentTarget[Yield, Await]
+        //
+        //   It is a Syntax Error if |DestructuringAssignmentTarget| is an |ArrayLiteral| or an |ObjectLiteral|.
+        if (
+          prop.type === "RestElement" &&
+          (prop.argument.type === "ArrayPattern" || prop.argument.type === "ObjectPattern")
+        ) {
+          this.raise(prop.argument.start, "Unexpected token")
+        }
+      }
+      break
+
+    case "Property":
+      // AssignmentProperty has type == "Property"
+      if (node.kind !== "init") this.raise(node.key.start, "Object pattern can't contain getter or setter")
+      this.toAssignable(node.value, isBinding)
+      break
+
+    case "ArrayExpression":
+      node.type = "ArrayPattern"
+      if (refDestructuringErrors) this.checkPatternErrors(refDestructuringErrors, true)
+      this.toAssignableList(node.elements, isBinding)
+      break
+
+    case "SpreadElement":
+      node.type = "RestElement"
+      this.toAssignable(node.argument, isBinding)
+      if (node.argument.type === "AssignmentPattern")
+        this.raise(node.argument.start, "Rest elements cannot have a default value")
+      break
+
+    case "AssignmentExpression":
+      if (node.operator !== "=") this.raise(node.left.end, "Only '=' operator can be used for specifying default value.")
+      node.type = "AssignmentPattern"
+      delete node.operator
+      this.toAssignable(node.left, isBinding)
+      // falls through to AssignmentPattern
+
+    case "AssignmentPattern":
+      break
+
+    case "ParenthesizedExpression":
+      this.toAssignable(node.expression, isBinding)
+      break
+
+    case "MemberExpression":
+      if (!isBinding) break
+
+    default:
+      this.raise(node.start, "Assigning to rvalue")
+    }
+  } else if (refDestructuringErrors) this.checkPatternErrors(refDestructuringErrors, true)
+  return node
+}
+
+// Convert list of expression atoms to binding list.
+
+pp.toAssignableList = function(exprList, isBinding) {
+  let end = exprList.length
+  for (let i = 0; i < end; i++) {
+    let elt = exprList[i]
+    if (elt) this.toAssignable(elt, isBinding)
+  }
+  if (end) {
+    let last = exprList[end - 1]
+    if (this.options.ecmaVersion === 6 && isBinding && last && last.type === "RestElement" && last.argument.type !== "Identifier")
+      this.unexpected(last.argument.start)
+  }
+  return exprList
+}
+
+// Parses spread element.
+
+pp.parseSpread = function(refDestructuringErrors) {
+  let node = this.startNode()
+  this.next()
+  node.argument = this.parseMaybeAssign(false, refDestructuringErrors)
+  return this.finishNode(node, "SpreadElement")
+}
+
+pp.parseRestBinding = function() {
+  let node = this.startNode()
+  this.next()
+
+  // RestElement inside of a function parameter must be an identifier
+  if (this.options.ecmaVersion === 6 && this.type !== tt.name)
+    this.unexpected()
+
+  node.argument = this.parseBindingAtom()
+
+  return this.finishNode(node, "RestElement")
+}
+
+// Parses lvalue (assignable) atom.
+
+pp.parseBindingAtom = function() {
+  if (this.options.ecmaVersion >= 6) {
+    switch (this.type) {
+    case tt.bracketL:
+      let node = this.startNode()
+      this.next()
+      node.elements = this.parseBindingList(tt.bracketR, true, true)
+      return this.finishNode(node, "ArrayPattern")
+
+    case tt.braceL:
+      return this.parseObj(true)
+    }
+  }
+  return this.parseIdent()
+}
+
+pp.parseBindingList = function(close, allowEmpty, allowTrailingComma) {
+  let elts = [], first = true
+  while (!this.eat(close)) {
+    if (first) first = false
+    else this.expect(tt.comma)
+    if (allowEmpty && this.type === tt.comma) {
+      elts.push(null)
+    } else if (allowTrailingComma && this.afterTrailingComma(close)) {
+      break
+    } else if (this.type === tt.ellipsis) {
+      let rest = this.parseRestBinding()
+      this.parseBindingListItem(rest)
+      elts.push(rest)
+      if (this.type === tt.comma) this.raise(this.start, "Comma is not permitted after the rest element")
+      this.expect(close)
+      break
+    } else {
+      let elem = this.parseMaybeDefault(this.start, this.startLoc)
+      this.parseBindingListItem(elem)
+      elts.push(elem)
+    }
+  }
+  return elts
+}
+
+pp.parseBindingListItem = function(param) {
+  return param
+}
+
+// Parses assignment pattern around given atom if possible.
+
+pp.parseMaybeDefault = function(startPos, startLoc, left) {
+  left = left || this.parseBindingAtom()
+  if (this.options.ecmaVersion < 6 || !this.eat(tt.eq)) return left
+  let node = this.startNodeAt(startPos, startLoc)
+  node.left = left
+  node.right = this.parseMaybeAssign()
+  return this.finishNode(node, "AssignmentPattern")
+}
+
+// Verify that a node is an lval — something that can be assigned
+// to.
+// bindingType can be either:
+// 'var' indicating that the lval creates a 'var' binding
+// 'let' indicating that the lval creates a lexical ('let' or 'const') binding
+// 'none' indicating that the binding should be checked for illegal identifiers, but not for duplicate references
+
+pp.checkLVal = function(expr, bindingType, checkClashes) {
+  switch (expr.type) {
+  case "Identifier":
+    if (this.strict && this.reservedWordsStrictBind.test(expr.name))
+      this.raiseRecoverable(expr.start, (bindingType ? "Binding " : "Assigning to ") + expr.name + " in strict mode")
+    if (checkClashes) {
+      if (has(checkClashes, expr.name))
+        this.raiseRecoverable(expr.start, "Argument name clash")
+      checkClashes[expr.name] = true
+    }
+    if (bindingType && bindingType !== "none") {
+      if (
+        bindingType === "var" && !this.canDeclareVarName(expr.name) ||
+        bindingType !== "var" && !this.canDeclareLexicalName(expr.name)
+      ) {
+        this.raiseRecoverable(expr.start, `Identifier '${expr.name}' has already been declared`)
+      }
+      if (bindingType === "var") {
+        this.declareVarName(expr.name)
+      } else {
+        this.declareLexicalName(expr.name)
+      }
+    }
+    break
+
+  case "MemberExpression":
+    if (bindingType) this.raiseRecoverable(expr.start, "Binding member expression")
+    break
+
+  case "ObjectPattern":
+    for (let prop of expr.properties)
+      this.checkLVal(prop, bindingType, checkClashes)
+    break
+
+  case "Property":
+    // AssignmentProperty has type == "Property"
+    this.checkLVal(expr.value, bindingType, checkClashes)
+    break
+
+  case "ArrayPattern":
+    for (let elem of expr.elements) {
+      if (elem) this.checkLVal(elem, bindingType, checkClashes)
+    }
+    break
+
+  case "AssignmentPattern":
+    this.checkLVal(expr.left, bindingType, checkClashes)
+    break
+
+  case "RestElement":
+    this.checkLVal(expr.argument, bindingType, checkClashes)
+    break
+
+  case "ParenthesizedExpression":
+    this.checkLVal(expr.expression, bindingType, checkClashes)
+    break
+
+  default:
+    this.raise(expr.start, (bindingType ? "Binding" : "Assigning to") + " rvalue")
+  }
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/node.js b/tools/tests/apps/modules/imports/links/acorn/src/node.js
new file mode 100644
index 0000000000..76b5b09825
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/node.js
@@ -0,0 +1,50 @@
+import {Parser} from "./state"
+import {SourceLocation} from "./locutil"
+
+export class Node {
+  constructor(parser, pos, loc) {
+    this.type = ""
+    this.start = pos
+    this.end = 0
+    if (parser.options.locations)
+      this.loc = new SourceLocation(parser, loc)
+    if (parser.options.directSourceFile)
+      this.sourceFile = parser.options.directSourceFile
+    if (parser.options.ranges)
+      this.range = [pos, 0]
+  }
+}
+
+// Start an AST node, attaching a start offset.
+
+const pp = Parser.prototype
+
+pp.startNode = function() {
+  return new Node(this, this.start, this.startLoc)
+}
+
+pp.startNodeAt = function(pos, loc) {
+  return new Node(this, pos, loc)
+}
+
+// Finish an AST node, adding `type` and `end` properties.
+
+function finishNodeAt(node, type, pos, loc) {
+  node.type = type
+  node.end = pos
+  if (this.options.locations)
+    node.loc.end = loc
+  if (this.options.ranges)
+    node.range[1] = pos
+  return node
+}
+
+pp.finishNode = function(node, type) {
+  return finishNodeAt.call(this, node, type, this.lastTokEnd, this.lastTokEndLoc)
+}
+
+// Finish node at given position
+
+pp.finishNodeAt = function(node, type, pos, loc) {
+  return finishNodeAt.call(this, node, type, pos, loc)
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/options.js b/tools/tests/apps/modules/imports/links/acorn/src/options.js
new file mode 100644
index 0000000000..9dda44ae88
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/options.js
@@ -0,0 +1,127 @@
+import {has, isArray} from "./util"
+import {SourceLocation} from "./locutil"
+
+// A second optional argument can be given to further configure
+// the parser process. These options are recognized:
+
+export const defaultOptions = {
+  // `ecmaVersion` indicates the ECMAScript version to parse. Must
+  // be either 3, 5, 6 (2015), 7 (2016), or 8 (2017). This influences support
+  // for strict mode, the set of reserved words, and support for
+  // new syntax features. The default is 7.
+  ecmaVersion: 7,
+  // `sourceType` indicates the mode the code should be parsed in.
+  // Can be either `"script"` or `"module"`. This influences global
+  // strict mode and parsing of `import` and `export` declarations.
+  sourceType: "script",
+  // `onInsertedSemicolon` can be a callback that will be called
+  // when a semicolon is automatically inserted. It will be passed
+  // th position of the comma as an offset, and if `locations` is
+  // enabled, it is given the location as a `{line, column}` object
+  // as second argument.
+  onInsertedSemicolon: null,
+  // `onTrailingComma` is similar to `onInsertedSemicolon`, but for
+  // trailing commas.
+  onTrailingComma: null,
+  // By default, reserved words are only enforced if ecmaVersion >= 5.
+  // Set `allowReserved` to a boolean value to explicitly turn this on
+  // an off. When this option has the value "never", reserved words
+  // and keywords can also not be used as property names.
+  allowReserved: null,
+  // When enabled, a return at the top level is not considered an
+  // error.
+  allowReturnOutsideFunction: false,
+  // When enabled, import/export statements are not constrained to
+  // appearing at the top of the program.
+  allowImportExportEverywhere: false,
+  // When enabled, hashbang directive in the beginning of file
+  // is allowed and treated as a line comment.
+  allowHashBang: false,
+  // When `locations` is on, `loc` properties holding objects with
+  // `start` and `end` properties in `{line, column}` form (with
+  // line being 1-based and column 0-based) will be attached to the
+  // nodes.
+  locations: false,
+  // A function can be passed as `onToken` option, which will
+  // cause Acorn to call that function with object in the same
+  // format as tokens returned from `tokenizer().getToken()`. Note
+  // that you are not allowed to call the parser from the
+  // callback—that will corrupt its internal state.
+  onToken: null,
+  // A function can be passed as `onComment` option, which will
+  // cause Acorn to call that function with `(block, text, start,
+  // end)` parameters whenever a comment is skipped. `block` is a
+  // boolean indicating whether this is a block (`/* */`) comment,
+  // `text` is the content of the comment, and `start` and `end` are
+  // character offsets that denote the start and end of the comment.
+  // When the `locations` option is on, two more parameters are
+  // passed, the full `{line, column}` locations of the start and
+  // end of the comments. Note that you are not allowed to call the
+  // parser from the callback—that will corrupt its internal state.
+  onComment: null,
+  // Nodes have their start and end characters offsets recorded in
+  // `start` and `end` properties (directly on the node, rather than
+  // the `loc` object, which holds line/column data. To also add a
+  // [semi-standardized][range] `range` property holding a `[start,
+  // end]` array with the same numbers, set the `ranges` option to
+  // `true`.
+  //
+  // [range]: https://bugzilla.mozilla.org/show_bug.cgi?id=745678
+  ranges: false,
+  // It is possible to parse multiple files into a single AST by
+  // passing the tree produced by parsing the first file as
+  // `program` option in subsequent parses. This will add the
+  // toplevel forms of the parsed file to the `Program` (top) node
+  // of an existing parse tree.
+  program: null,
+  // When `locations` is on, you can pass this to record the source
+  // file in every node's `loc` object.
+  sourceFile: null,
+  // This value, if given, is stored in every node, whether
+  // `locations` is on or off.
+  directSourceFile: null,
+  // When enabled, parenthesized expressions are represented by
+  // (non-standard) ParenthesizedExpression nodes
+  preserveParens: false,
+  plugins: {}
+}
+
+// Interpret and default an options object
+
+export function getOptions(opts) {
+  let options = {}
+
+  for (let opt in defaultOptions)
+    options[opt] = opts && has(opts, opt) ? opts[opt] : defaultOptions[opt]
+
+  if (options.ecmaVersion >= 2015)
+    options.ecmaVersion -= 2009
+
+  if (options.allowReserved == null)
+    options.allowReserved = options.ecmaVersion < 5
+
+  if (isArray(options.onToken)) {
+    let tokens = options.onToken
+    options.onToken = (token) => tokens.push(token)
+  }
+  if (isArray(options.onComment))
+    options.onComment = pushComment(options, options.onComment)
+
+  return options
+}
+
+function pushComment(options, array) {
+  return function(block, text, start, end, startLoc, endLoc) {
+    let comment = {
+      type: block ? "Block" : "Line",
+      value: text,
+      start: start,
+      end: end
+    }
+    if (options.locations)
+      comment.loc = new SourceLocation(this, startLoc, endLoc)
+    if (options.ranges)
+      comment.range = [start, end]
+    array.push(comment)
+  }
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/parseutil.js b/tools/tests/apps/modules/imports/links/acorn/src/parseutil.js
new file mode 100644
index 0000000000..e1736372e5
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/parseutil.js
@@ -0,0 +1,137 @@
+import {types as tt} from "./tokentype"
+import {Parser} from "./state"
+import {lineBreak, skipWhiteSpace} from "./whitespace"
+
+const pp = Parser.prototype
+
+// ## Parser utilities
+
+const literal = /^(?:'((?:\\.|[^'])*?)'|"((?:\\.|[^"])*?)"|;)/
+pp.strictDirective = function(start) {
+  for (;;) {
+    skipWhiteSpace.lastIndex = start
+    start += skipWhiteSpace.exec(this.input)[0].length
+    let match = literal.exec(this.input.slice(start))
+    if (!match) return false
+    if ((match[1] || match[2]) == "use strict") return true
+    start += match[0].length
+  }
+}
+
+// Predicate that tests whether the next token is of the given
+// type, and if yes, consumes it as a side effect.
+
+pp.eat = function(type) {
+  if (this.type === type) {
+    this.next()
+    return true
+  } else {
+    return false
+  }
+}
+
+// Tests whether parsed token is a contextual keyword.
+
+pp.isContextual = function(name) {
+  return this.type === tt.name && this.value === name && !this.containsEsc
+}
+
+// Consumes contextual keyword if possible.
+
+pp.eatContextual = function(name) {
+  if (!this.isContextual(name)) return false
+  this.next()
+  return true
+}
+
+// Asserts that following token is given contextual keyword.
+
+pp.expectContextual = function(name) {
+  if (!this.eatContextual(name)) this.unexpected()
+}
+
+// Test whether a semicolon can be inserted at the current position.
+
+pp.canInsertSemicolon = function() {
+  return this.type === tt.eof ||
+    this.type === tt.braceR ||
+    lineBreak.test(this.input.slice(this.lastTokEnd, this.start))
+}
+
+pp.insertSemicolon = function() {
+  if (this.canInsertSemicolon()) {
+    if (this.options.onInsertedSemicolon)
+      this.options.onInsertedSemicolon(this.lastTokEnd, this.lastTokEndLoc)
+    return true
+  }
+}
+
+// Consume a semicolon, or, failing that, see if we are allowed to
+// pretend that there is a semicolon at this position.
+
+pp.semicolon = function() {
+  if (!this.eat(tt.semi) && !this.insertSemicolon()) this.unexpected()
+}
+
+pp.afterTrailingComma = function(tokType, notNext) {
+  if (this.type == tokType) {
+    if (this.options.onTrailingComma)
+      this.options.onTrailingComma(this.lastTokStart, this.lastTokStartLoc)
+    if (!notNext)
+      this.next()
+    return true
+  }
+}
+
+// Expect a token of a given type. If found, consume it, otherwise,
+// raise an unexpected token error.
+
+pp.expect = function(type) {
+  this.eat(type) || this.unexpected()
+}
+
+// Raise an unexpected token error.
+
+pp.unexpected = function(pos) {
+  this.raise(pos != null ? pos : this.start, "Unexpected token")
+}
+
+export function DestructuringErrors() {
+  this.shorthandAssign =
+  this.trailingComma =
+  this.parenthesizedAssign =
+  this.parenthesizedBind =
+  this.doubleProto =
+    -1
+}
+
+pp.checkPatternErrors = function(refDestructuringErrors, isAssign) {
+  if (!refDestructuringErrors) return
+  if (refDestructuringErrors.trailingComma > -1)
+    this.raiseRecoverable(refDestructuringErrors.trailingComma, "Comma is not permitted after the rest element")
+  let parens = isAssign ? refDestructuringErrors.parenthesizedAssign : refDestructuringErrors.parenthesizedBind
+  if (parens > -1) this.raiseRecoverable(parens, "Parenthesized pattern")
+}
+
+pp.checkExpressionErrors = function(refDestructuringErrors, andThrow) {
+  if (!refDestructuringErrors) return false
+  let {shorthandAssign, doubleProto} = refDestructuringErrors
+  if (!andThrow) return shorthandAssign >= 0 || doubleProto >= 0
+  if (shorthandAssign >= 0)
+    this.raise(shorthandAssign, "Shorthand property assignments are valid only in destructuring patterns")
+  if (doubleProto >= 0)
+    this.raiseRecoverable(doubleProto, "Redefinition of __proto__ property")
+}
+
+pp.checkYieldAwaitInDefaultParams = function() {
+  if (this.yieldPos && (!this.awaitPos || this.yieldPos < this.awaitPos))
+    this.raise(this.yieldPos, "Yield expression cannot be a default value")
+  if (this.awaitPos)
+    this.raise(this.awaitPos, "Await expression cannot be a default value")
+}
+
+pp.isSimpleAssignTarget = function(expr) {
+  if (expr.type === "ParenthesizedExpression")
+    return this.isSimpleAssignTarget(expr.expression)
+  return expr.type === "Identifier" || expr.type === "MemberExpression"
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/regexp.js b/tools/tests/apps/modules/imports/links/acorn/src/regexp.js
new file mode 100644
index 0000000000..c5953e3012
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/regexp.js
@@ -0,0 +1,1042 @@
+import {isIdentifierStart, isIdentifierChar} from "./identifier.js"
+import {Parser} from "./state.js"
+import UNICODE_PROPERTY_VALUES from "./unicode-property-data.js"
+
+const pp = Parser.prototype
+
+export class RegExpValidationState {
+  constructor(parser) {
+    this.parser = parser
+    this.validFlags = `gim${parser.options.ecmaVersion >= 6 ? "uy" : ""}${parser.options.ecmaVersion >= 9 ? "s" : ""}`
+    this.source = ""
+    this.flags = ""
+    this.start = 0
+    this.switchU = false
+    this.switchN = false
+    this.pos = 0
+    this.lastIntValue = 0
+    this.lastStringValue = ""
+    this.lastAssertionIsQuantifiable = false
+    this.numCapturingParens = 0
+    this.maxBackReference = 0
+    this.groupNames = []
+    this.backReferenceNames = []
+  }
+
+  reset(start, pattern, flags) {
+    const unicode = flags.indexOf("u") !== -1
+    this.start = start | 0
+    this.source = pattern + ""
+    this.flags = flags
+    this.switchU = unicode && this.parser.options.ecmaVersion >= 6
+    this.switchN = unicode && this.parser.options.ecmaVersion >= 9
+  }
+
+  raise(message) {
+    this.parser.raiseRecoverable(this.start, `Invalid regular expression: /${this.source}/: ${message}`)
+  }
+
+  // If u flag is given, this returns the code point at the index (it combines a surrogate pair).
+  // Otherwise, this returns the code unit of the index (can be a part of a surrogate pair).
+  at(i) {
+    const s = this.source
+    const l = s.length
+    if (i >= l) {
+      return -1
+    }
+    const c = s.charCodeAt(i)
+    if (!this.switchU || c <= 0xD7FF || c >= 0xE000 || i + 1 >= l) {
+      return c
+    }
+    return (c << 10) + s.charCodeAt(i + 1) - 0x35FDC00
+  }
+
+  nextIndex(i) {
+    const s = this.source
+    const l = s.length
+    if (i >= l) {
+      return l
+    }
+    const c = s.charCodeAt(i)
+    if (!this.switchU || c <= 0xD7FF || c >= 0xE000 || i + 1 >= l) {
+      return i + 1
+    }
+    return i + 2
+  }
+
+  current() {
+    return this.at(this.pos)
+  }
+
+  lookahead() {
+    return this.at(this.nextIndex(this.pos))
+  }
+
+  advance() {
+    this.pos = this.nextIndex(this.pos)
+  }
+
+  eat(ch) {
+    if (this.current() === ch) {
+      this.advance()
+      return true
+    }
+    return false
+  }
+}
+
+function codePointToString(ch) {
+  if (ch <= 0xFFFF) return String.fromCharCode(ch)
+  ch -= 0x10000
+  return String.fromCharCode((ch >> 10) + 0xD800, (ch & 0x03FF) + 0xDC00)
+}
+
+/**
+ * Validate the flags part of a given RegExpLiteral.
+ *
+ * @param {RegExpValidationState} state The state to validate RegExp.
+ * @returns {void}
+ */
+pp.validateRegExpFlags = function(state) {
+  const validFlags = state.validFlags
+  const flags = state.flags
+
+  for (let i = 0; i < flags.length; i++) {
+    const flag = flags.charAt(i)
+    if (validFlags.indexOf(flag) == -1) {
+      this.raise(state.start, "Invalid regular expression flag")
+    }
+    if (flags.indexOf(flag, i + 1) > -1) {
+      this.raise(state.start, "Duplicate regular expression flag")
+    }
+  }
+}
+
+/**
+ * Validate the pattern part of a given RegExpLiteral.
+ *
+ * @param {RegExpValidationState} state The state to validate RegExp.
+ * @returns {void}
+ */
+pp.validateRegExpPattern = function(state) {
+  this.regexp_pattern(state)
+
+  // The goal symbol for the parse is |Pattern[~U, ~N]|. If the result of
+  // parsing contains a |GroupName|, reparse with the goal symbol
+  // |Pattern[~U, +N]| and use this result instead. Throw a *SyntaxError*
+  // exception if _P_ did not conform to the grammar, if any elements of _P_
+  // were not matched by the parse, or if any Early Error conditions exist.
+  if (!state.switchN && this.options.ecmaVersion >= 9 && state.groupNames.length > 0) {
+    state.switchN = true
+    this.regexp_pattern(state)
+  }
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-Pattern
+pp.regexp_pattern = function(state) {
+  state.pos = 0
+  state.lastIntValue = 0
+  state.lastStringValue = ""
+  state.lastAssertionIsQuantifiable = false
+  state.numCapturingParens = 0
+  state.maxBackReference = 0
+  state.groupNames.length = 0
+  state.backReferenceNames.length = 0
+
+  this.regexp_disjunction(state)
+
+  if (state.pos !== state.source.length) {
+    // Make the same messages as V8.
+    if (state.eat(0x29 /* ) */)) {
+      state.raise("Unmatched ')'")
+    }
+    if (state.eat(0x5D /* [ */) || state.eat(0x7D /* } */)) {
+      state.raise("Lone quantifier brackets")
+    }
+  }
+  if (state.maxBackReference > state.numCapturingParens) {
+    state.raise("Invalid escape")
+  }
+  for (const name of state.backReferenceNames) {
+    if (state.groupNames.indexOf(name) === -1) {
+      state.raise("Invalid named capture referenced")
+    }
+  }
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-Disjunction
+pp.regexp_disjunction = function(state) {
+  this.regexp_alternative(state)
+  while (state.eat(0x7C /* | */)) {
+    this.regexp_alternative(state)
+  }
+
+  // Make the same message as V8.
+  if (this.regexp_eatQuantifier(state, true)) {
+    state.raise("Nothing to repeat")
+  }
+  if (state.eat(0x7B /* { */)) {
+    state.raise("Lone quantifier brackets")
+  }
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-Alternative
+pp.regexp_alternative = function(state) {
+  while (state.pos < state.source.length && this.regexp_eatTerm(state))
+    ;
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-Term
+pp.regexp_eatTerm = function(state) {
+  if (this.regexp_eatAssertion(state)) {
+    // Handle `QuantifiableAssertion Quantifier` alternative.
+    // `state.lastAssertionIsQuantifiable` is true if the last eaten Assertion
+    // is a QuantifiableAssertion.
+    if (state.lastAssertionIsQuantifiable && this.regexp_eatQuantifier(state)) {
+      // Make the same message as V8.
+      if (state.switchU) {
+        state.raise("Invalid quantifier")
+      }
+    }
+    return true
+  }
+
+  if (state.switchU ? this.regexp_eatAtom(state) : this.regexp_eatExtendedAtom(state)) {
+    this.regexp_eatQuantifier(state)
+    return true
+  }
+
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-Assertion
+pp.regexp_eatAssertion = function(state) {
+  const start = state.pos
+  state.lastAssertionIsQuantifiable = false
+
+  // ^, $
+  if (state.eat(0x5E /* ^ */) || state.eat(0x24 /* $ */)) {
+    return true
+  }
+
+  // \b \B
+  if (state.eat(0x5C /* \ */)) {
+    if (state.eat(0x42 /* B */) || state.eat(0x62 /* b */)) {
+      return true
+    }
+    state.pos = start
+  }
+
+  // Lookahead / Lookbehind
+  if (state.eat(0x28 /* ( */) && state.eat(0x3F /* ? */)) {
+    let lookbehind = false
+    if (this.options.ecmaVersion >= 9) {
+      lookbehind = state.eat(0x3C /* < */)
+    }
+    if (state.eat(0x3D /* = */) || state.eat(0x21 /* ! */)) {
+      this.regexp_disjunction(state)
+      if (!state.eat(0x29 /* ) */)) {
+        state.raise("Unterminated group")
+      }
+      state.lastAssertionIsQuantifiable = !lookbehind
+      return true
+    }
+  }
+
+  state.pos = start
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-Quantifier
+pp.regexp_eatQuantifier = function(state, noError = false) {
+  if (this.regexp_eatQuantifierPrefix(state, noError)) {
+    state.eat(0x3F /* ? */)
+    return true
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-QuantifierPrefix
+pp.regexp_eatQuantifierPrefix = function(state, noError) {
+  return (
+    state.eat(0x2A /* * */) ||
+    state.eat(0x2B /* + */) ||
+    state.eat(0x3F /* ? */) ||
+    this.regexp_eatBracedQuantifier(state, noError)
+  )
+}
+pp.regexp_eatBracedQuantifier = function(state, noError) {
+  const start = state.pos
+  if (state.eat(0x7B /* { */)) {
+    let min = 0, max = -1
+    if (this.regexp_eatDecimalDigits(state)) {
+      min = state.lastIntValue
+      if (state.eat(0x2C /* , */) && this.regexp_eatDecimalDigits(state)) {
+        max = state.lastIntValue
+      }
+      if (state.eat(0x7D /* } */)) {
+        // SyntaxError in https://www.ecma-international.org/ecma-262/8.0/#sec-term
+        if (max !== -1 && max < min && !noError) {
+          state.raise("numbers out of order in {} quantifier")
+        }
+        return true
+      }
+    }
+    if (state.switchU && !noError) {
+      state.raise("Incomplete quantifier")
+    }
+    state.pos = start
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-Atom
+pp.regexp_eatAtom = function(state) {
+  return (
+    this.regexp_eatPatternCharacters(state) ||
+    state.eat(0x2E /* . */) ||
+    this.regexp_eatReverseSolidusAtomEscape(state) ||
+    this.regexp_eatCharacterClass(state) ||
+    this.regexp_eatUncapturingGroup(state) ||
+    this.regexp_eatCapturingGroup(state)
+  )
+}
+pp.regexp_eatReverseSolidusAtomEscape = function(state) {
+  const start = state.pos
+  if (state.eat(0x5C /* \ */)) {
+    if (this.regexp_eatAtomEscape(state)) {
+      return true
+    }
+    state.pos = start
+  }
+  return false
+}
+pp.regexp_eatUncapturingGroup = function(state) {
+  const start = state.pos
+  if (state.eat(0x28 /* ( */)) {
+    if (state.eat(0x3F /* ? */) && state.eat(0x3A /* : */)) {
+      this.regexp_disjunction(state)
+      if (state.eat(0x29 /* ) */)) {
+        return true
+      }
+      state.raise("Unterminated group")
+    }
+    state.pos = start
+  }
+  return false
+}
+pp.regexp_eatCapturingGroup = function(state) {
+  if (state.eat(0x28 /* ( */)) {
+    if (this.options.ecmaVersion >= 9) {
+      this.regexp_groupSpecifier(state)
+    } else if (state.current() === 0x3F /* ? */) {
+      state.raise("Invalid group")
+    }
+    this.regexp_disjunction(state)
+    if (state.eat(0x29 /* ) */)) {
+      state.numCapturingParens += 1
+      return true
+    }
+    state.raise("Unterminated group")
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-ExtendedAtom
+pp.regexp_eatExtendedAtom = function(state) {
+  return (
+    state.eat(0x2E /* . */) ||
+    this.regexp_eatReverseSolidusAtomEscape(state) ||
+    this.regexp_eatCharacterClass(state) ||
+    this.regexp_eatUncapturingGroup(state) ||
+    this.regexp_eatCapturingGroup(state) ||
+    this.regexp_eatInvalidBracedQuantifier(state) ||
+    this.regexp_eatExtendedPatternCharacter(state)
+  )
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-InvalidBracedQuantifier
+pp.regexp_eatInvalidBracedQuantifier = function(state) {
+  if (this.regexp_eatBracedQuantifier(state, true)) {
+    state.raise("Nothing to repeat")
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-SyntaxCharacter
+pp.regexp_eatSyntaxCharacter = function(state) {
+  const ch = state.current()
+  if (isSyntaxCharacter(ch)) {
+    state.lastIntValue = ch
+    state.advance()
+    return true
+  }
+  return false
+}
+function isSyntaxCharacter(ch) {
+  return (
+    ch === 0x24 /* $ */ ||
+    ch >= 0x28 /* ( */ && ch <= 0x2B /* + */ ||
+    ch === 0x2E /* . */ ||
+    ch === 0x3F /* ? */ ||
+    ch >= 0x5B /* [ */ && ch <= 0x5E /* ^ */ ||
+    ch >= 0x7B /* { */ && ch <= 0x7D /* } */
+  )
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-PatternCharacter
+// But eat eager.
+pp.regexp_eatPatternCharacters = function(state) {
+  const start = state.pos
+  let ch = 0
+  while ((ch = state.current()) !== -1 && !isSyntaxCharacter(ch)) {
+    state.advance()
+  }
+  return state.pos !== start
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-ExtendedPatternCharacter
+pp.regexp_eatExtendedPatternCharacter = function(state) {
+  const ch = state.current()
+  if (
+    ch !== -1 &&
+    ch !== 0x24 /* $ */ &&
+    !(ch >= 0x28 /* ( */ && ch <= 0x2B /* + */) &&
+    ch !== 0x2E /* . */ &&
+    ch !== 0x3F /* ? */ &&
+    ch !== 0x5B /* [ */ &&
+    ch !== 0x5E /* ^ */ &&
+    ch !== 0x7C /* | */
+  ) {
+    state.advance()
+    return true
+  }
+  return false
+}
+
+// GroupSpecifier[U] ::
+//   [empty]
+//   `?` GroupName[?U]
+pp.regexp_groupSpecifier = function(state) {
+  if (state.eat(0x3F /* ? */)) {
+    if (this.regexp_eatGroupName(state)) {
+      if (state.groupNames.indexOf(state.lastStringValue) !== -1) {
+        state.raise("Duplicate capture group name")
+      }
+      state.groupNames.push(state.lastStringValue)
+      return
+    }
+    state.raise("Invalid group")
+  }
+}
+
+// GroupName[U] ::
+//   `<` RegExpIdentifierName[?U] `>`
+// Note: this updates `state.lastStringValue` property with the eaten name.
+pp.regexp_eatGroupName = function(state) {
+  state.lastStringValue = ""
+  if (state.eat(0x3C /* < */)) {
+    if (this.regexp_eatRegExpIdentifierName(state) && state.eat(0x3E /* > */)) {
+      return true
+    }
+    state.raise("Invalid capture group name")
+  }
+  return false
+}
+
+// RegExpIdentifierName[U] ::
+//   RegExpIdentifierStart[?U]
+//   RegExpIdentifierName[?U] RegExpIdentifierPart[?U]
+// Note: this updates `state.lastStringValue` property with the eaten name.
+pp.regexp_eatRegExpIdentifierName = function(state) {
+  state.lastStringValue = ""
+  if (this.regexp_eatRegExpIdentifierStart(state)) {
+    state.lastStringValue += codePointToString(state.lastIntValue)
+    while (this.regexp_eatRegExpIdentifierPart(state)) {
+      state.lastStringValue += codePointToString(state.lastIntValue)
+    }
+    return true
+  }
+  return false
+}
+
+// RegExpIdentifierStart[U] ::
+//   UnicodeIDStart
+//   `$`
+//   `_`
+//   `\` RegExpUnicodeEscapeSequence[?U]
+pp.regexp_eatRegExpIdentifierStart = function(state) {
+  const start = state.pos
+  let ch = state.current()
+  state.advance()
+
+  if (ch === 0x5C /* \ */ && this.regexp_eatRegExpUnicodeEscapeSequence(state)) {
+    ch = state.lastIntValue
+  }
+  if (isRegExpIdentifierStart(ch)) {
+    state.lastIntValue = ch
+    return true
+  }
+
+  state.pos = start
+  return false
+}
+function isRegExpIdentifierStart(ch) {
+  return isIdentifierStart(ch, true) || ch === 0x24 /* $ */ || ch === 0x5F /* _ */
+}
+
+// RegExpIdentifierPart[U] ::
+//   UnicodeIDContinue
+//   `$`
+//   `_`
+//   `\` RegExpUnicodeEscapeSequence[?U]
+//   <ZWNJ>
+//   <ZWJ>
+pp.regexp_eatRegExpIdentifierPart = function(state) {
+  const start = state.pos
+  let ch = state.current()
+  state.advance()
+
+  if (ch === 0x5C /* \ */ && this.regexp_eatRegExpUnicodeEscapeSequence(state)) {
+    ch = state.lastIntValue
+  }
+  if (isRegExpIdentifierPart(ch)) {
+    state.lastIntValue = ch
+    return true
+  }
+
+  state.pos = start
+  return false
+}
+function isRegExpIdentifierPart(ch) {
+  return isIdentifierChar(ch, true) || ch === 0x24 /* $ */ || ch === 0x5F /* _ */ || ch === 0x200C /* <ZWNJ> */ || ch === 0x200D /* <ZWJ> */
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-AtomEscape
+pp.regexp_eatAtomEscape = function(state) {
+  if (
+    this.regexp_eatBackReference(state) ||
+    this.regexp_eatCharacterClassEscape(state) ||
+    this.regexp_eatCharacterEscape(state) ||
+    (state.switchN && this.regexp_eatKGroupName(state))
+  ) {
+    return true
+  }
+  if (state.switchU) {
+    // Make the same message as V8.
+    if (state.current() === 0x63 /* c */) {
+      state.raise("Invalid unicode escape")
+    }
+    state.raise("Invalid escape")
+  }
+  return false
+}
+pp.regexp_eatBackReference = function(state) {
+  const start = state.pos
+  if (this.regexp_eatDecimalEscape(state)) {
+    const n = state.lastIntValue
+    if (state.switchU) {
+      // For SyntaxError in https://www.ecma-international.org/ecma-262/8.0/#sec-atomescape
+      if (n > state.maxBackReference) {
+        state.maxBackReference = n
+      }
+      return true
+    }
+    if (n <= state.numCapturingParens) {
+      return true
+    }
+    state.pos = start
+  }
+  return false
+}
+pp.regexp_eatKGroupName = function(state) {
+  if (state.eat(0x6B /* k */)) {
+    if (this.regexp_eatGroupName(state)) {
+      state.backReferenceNames.push(state.lastStringValue)
+      return true
+    }
+    state.raise("Invalid named reference")
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-CharacterEscape
+pp.regexp_eatCharacterEscape = function(state) {
+  return (
+    this.regexp_eatControlEscape(state) ||
+    this.regexp_eatCControlLetter(state) ||
+    this.regexp_eatZero(state) ||
+    this.regexp_eatHexEscapeSequence(state) ||
+    this.regexp_eatRegExpUnicodeEscapeSequence(state) ||
+    (!state.switchU && this.regexp_eatLegacyOctalEscapeSequence(state)) ||
+    this.regexp_eatIdentityEscape(state)
+  )
+}
+pp.regexp_eatCControlLetter = function(state) {
+  const start = state.pos
+  if (state.eat(0x63 /* c */)) {
+    if (this.regexp_eatControlLetter(state)) {
+      return true
+    }
+    state.pos = start
+  }
+  return false
+}
+pp.regexp_eatZero = function(state) {
+  if (state.current() === 0x30 /* 0 */ && !isDecimalDigit(state.lookahead())) {
+    state.lastIntValue = 0
+    state.advance()
+    return true
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-ControlEscape
+pp.regexp_eatControlEscape = function(state) {
+  const ch = state.current()
+  if (ch === 0x74 /* t */) {
+    state.lastIntValue = 0x09 /* \t */
+    state.advance()
+    return true
+  }
+  if (ch === 0x6E /* n */) {
+    state.lastIntValue = 0x0A /* \n */
+    state.advance()
+    return true
+  }
+  if (ch === 0x76 /* v */) {
+    state.lastIntValue = 0x0B /* \v */
+    state.advance()
+    return true
+  }
+  if (ch === 0x66 /* f */) {
+    state.lastIntValue = 0x0C /* \f */
+    state.advance()
+    return true
+  }
+  if (ch === 0x72 /* r */) {
+    state.lastIntValue = 0x0D /* \r */
+    state.advance()
+    return true
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-ControlLetter
+pp.regexp_eatControlLetter = function(state) {
+  const ch = state.current()
+  if (isControlLetter(ch)) {
+    state.lastIntValue = ch % 0x20
+    state.advance()
+    return true
+  }
+  return false
+}
+function isControlLetter(ch) {
+  return (
+    (ch >= 0x41 /* A */ && ch <= 0x5A /* Z */) ||
+    (ch >= 0x61 /* a */ && ch <= 0x7A /* z */)
+  )
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-RegExpUnicodeEscapeSequence
+pp.regexp_eatRegExpUnicodeEscapeSequence = function(state) {
+  const start = state.pos
+
+  if (state.eat(0x75 /* u */)) {
+    if (this.regexp_eatFixedHexDigits(state, 4)) {
+      const lead = state.lastIntValue
+      if (state.switchU && lead >= 0xD800 && lead <= 0xDBFF) {
+        const leadSurrogateEnd = state.pos
+        if (state.eat(0x5C /* \ */) && state.eat(0x75 /* u */) && this.regexp_eatFixedHexDigits(state, 4)) {
+          const trail = state.lastIntValue
+          if (trail >= 0xDC00 && trail <= 0xDFFF) {
+            state.lastIntValue = (lead - 0xD800) * 0x400 + (trail - 0xDC00) + 0x10000
+            return true
+          }
+        }
+        state.pos = leadSurrogateEnd
+        state.lastIntValue = lead
+      }
+      return true
+    }
+    if (
+      state.switchU &&
+      state.eat(0x7B /* { */) &&
+      this.regexp_eatHexDigits(state) &&
+      state.eat(0x7D /* } */) &&
+      isValidUnicode(state.lastIntValue)
+    ) {
+      return true
+    }
+    if (state.switchU) {
+      state.raise("Invalid unicode escape")
+    }
+    state.pos = start
+  }
+
+  return false
+}
+function isValidUnicode(ch) {
+  return ch >= 0 && ch <= 0x10FFFF
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-IdentityEscape
+pp.regexp_eatIdentityEscape = function(state) {
+  if (state.switchU) {
+    if (this.regexp_eatSyntaxCharacter(state)) {
+      return true
+    }
+    if (state.eat(0x2F /* / */)) {
+      state.lastIntValue = 0x2F /* / */
+      return true
+    }
+    return false
+  }
+
+  const ch = state.current()
+  if (ch !== 0x63 /* c */ && (!state.switchN || ch !== 0x6B /* k */)) {
+    state.lastIntValue = ch
+    state.advance()
+    return true
+  }
+
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-DecimalEscape
+pp.regexp_eatDecimalEscape = function(state) {
+  state.lastIntValue = 0
+  let ch = state.current()
+  if (ch >= 0x31 /* 1 */ && ch <= 0x39 /* 9 */) {
+    do {
+      state.lastIntValue = 10 * state.lastIntValue + (ch - 0x30 /* 0 */)
+      state.advance()
+    } while ((ch = state.current()) >= 0x30 /* 0 */ && ch <= 0x39 /* 9 */)
+    return true
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-CharacterClassEscape
+pp.regexp_eatCharacterClassEscape = function(state) {
+  const ch = state.current()
+
+  if (isCharacterClassEscape(ch)) {
+    state.lastIntValue = -1
+    state.advance()
+    return true
+  }
+
+  if (
+    state.switchU &&
+    this.options.ecmaVersion >= 9 &&
+    (ch === 0x50 /* P */ || ch === 0x70 /* p */)
+  ) {
+    state.lastIntValue = -1
+    state.advance()
+    if (
+      state.eat(0x7B /* { */) &&
+      this.regexp_eatUnicodePropertyValueExpression(state) &&
+      state.eat(0x7D /* } */)
+    ) {
+      return true
+    }
+    state.raise("Invalid property name")
+  }
+
+  return false
+}
+function isCharacterClassEscape(ch) {
+  return (
+    ch === 0x64 /* d */ ||
+    ch === 0x44 /* D */ ||
+    ch === 0x73 /* s */ ||
+    ch === 0x53 /* S */ ||
+    ch === 0x77 /* w */ ||
+    ch === 0x57 /* W */
+  )
+}
+
+// UnicodePropertyValueExpression ::
+//   UnicodePropertyName `=` UnicodePropertyValue
+//   LoneUnicodePropertyNameOrValue
+pp.regexp_eatUnicodePropertyValueExpression = function(state) {
+  const start = state.pos
+
+  // UnicodePropertyName `=` UnicodePropertyValue
+  if (this.regexp_eatUnicodePropertyName(state) && state.eat(0x3D /* = */)) {
+    const name = state.lastStringValue
+    if (this.regexp_eatUnicodePropertyValue(state)) {
+      const value = state.lastStringValue
+      this.regexp_validateUnicodePropertyNameAndValue(state, name, value)
+      return true
+    }
+  }
+  state.pos = start
+
+  // LoneUnicodePropertyNameOrValue
+  if (this.regexp_eatLoneUnicodePropertyNameOrValue(state)) {
+    const nameOrValue = state.lastStringValue
+    this.regexp_validateUnicodePropertyNameOrValue(state, nameOrValue)
+    return true
+  }
+  return false
+}
+pp.regexp_validateUnicodePropertyNameAndValue = function(state, name, value) {
+  if (!UNICODE_PROPERTY_VALUES.hasOwnProperty(name) || UNICODE_PROPERTY_VALUES[name].indexOf(value) === -1) {
+    state.raise("Invalid property name")
+  }
+}
+pp.regexp_validateUnicodePropertyNameOrValue = function(state, nameOrValue) {
+  if (UNICODE_PROPERTY_VALUES.$LONE.indexOf(nameOrValue) === -1) {
+    state.raise("Invalid property name")
+  }
+}
+
+// UnicodePropertyName ::
+//   UnicodePropertyNameCharacters
+pp.regexp_eatUnicodePropertyName = function(state) {
+  let ch = 0
+  state.lastStringValue = ""
+  while (isUnicodePropertyNameCharacter(ch = state.current())) {
+    state.lastStringValue += codePointToString(ch)
+    state.advance()
+  }
+  return state.lastStringValue !== ""
+}
+function isUnicodePropertyNameCharacter(ch) {
+  return isControlLetter(ch) || ch === 0x5F /* _ */
+}
+
+// UnicodePropertyValue ::
+//   UnicodePropertyValueCharacters
+pp.regexp_eatUnicodePropertyValue = function(state) {
+  let ch = 0
+  state.lastStringValue = ""
+  while (isUnicodePropertyValueCharacter(ch = state.current())) {
+    state.lastStringValue += codePointToString(ch)
+    state.advance()
+  }
+  return state.lastStringValue !== ""
+}
+function isUnicodePropertyValueCharacter(ch) {
+  return isUnicodePropertyNameCharacter(ch) || isDecimalDigit(ch)
+}
+
+// LoneUnicodePropertyNameOrValue ::
+//   UnicodePropertyValueCharacters
+pp.regexp_eatLoneUnicodePropertyNameOrValue = function(state) {
+  return this.regexp_eatUnicodePropertyValue(state)
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-CharacterClass
+pp.regexp_eatCharacterClass = function(state) {
+  if (state.eat(0x5B /* [ */)) {
+    state.eat(0x5E /* ^ */)
+    this.regexp_classRanges(state)
+    if (state.eat(0x5D /* [ */)) {
+      return true
+    }
+    // Unreachable since it threw "unterminated regular expression" error before.
+    state.raise("Unterminated character class")
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-ClassRanges
+// https://www.ecma-international.org/ecma-262/8.0/#prod-NonemptyClassRanges
+// https://www.ecma-international.org/ecma-262/8.0/#prod-NonemptyClassRangesNoDash
+pp.regexp_classRanges = function(state) {
+  while (this.regexp_eatClassAtom(state)) {
+    const left = state.lastIntValue
+    if (state.eat(0x2D /* - */) && this.regexp_eatClassAtom(state)) {
+      const right = state.lastIntValue
+      if (state.switchU && (left === -1 || right === -1)) {
+        state.raise("Invalid character class")
+      }
+      if (left !== -1 && right !== -1 && left > right) {
+        state.raise("Range out of order in character class")
+      }
+    }
+  }
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-ClassAtom
+// https://www.ecma-international.org/ecma-262/8.0/#prod-ClassAtomNoDash
+pp.regexp_eatClassAtom = function(state) {
+  const start = state.pos
+
+  if (state.eat(0x5C /* \ */)) {
+    if (this.regexp_eatClassEscape(state)) {
+      return true
+    }
+    if (state.switchU) {
+      // Make the same message as V8.
+      const ch = state.current()
+      if (ch === 0x63 /* c */ || isOctalDigit(ch)) {
+        state.raise("Invalid class escape")
+      }
+      state.raise("Invalid escape")
+    }
+    state.pos = start
+  }
+
+  const ch = state.current()
+  if (ch !== 0x5D /* [ */) {
+    state.lastIntValue = ch
+    state.advance()
+    return true
+  }
+
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-ClassEscape
+pp.regexp_eatClassEscape = function(state) {
+  const start = state.pos
+
+  if (state.eat(0x62 /* b */)) {
+    state.lastIntValue = 0x08 /* <BS> */
+    return true
+  }
+
+  if (state.switchU && state.eat(0x2D /* - */)) {
+    state.lastIntValue = 0x2D /* - */
+    return true
+  }
+
+  if (!state.switchU && state.eat(0x63 /* c */)) {
+    if (this.regexp_eatClassControlLetter(state)) {
+      return true
+    }
+    state.pos = start
+  }
+
+  return (
+    this.regexp_eatCharacterClassEscape(state) ||
+    this.regexp_eatCharacterEscape(state)
+  )
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-ClassControlLetter
+pp.regexp_eatClassControlLetter = function(state) {
+  const ch = state.current()
+  if (isDecimalDigit(ch) || ch === 0x5F /* _ */) {
+    state.lastIntValue = ch % 0x20
+    state.advance()
+    return true
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-HexEscapeSequence
+pp.regexp_eatHexEscapeSequence = function(state) {
+  const start = state.pos
+  if (state.eat(0x78 /* x */)) {
+    if (this.regexp_eatFixedHexDigits(state, 2)) {
+      return true
+    }
+    if (state.switchU) {
+      state.raise("Invalid escape")
+    }
+    state.pos = start
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-DecimalDigits
+pp.regexp_eatDecimalDigits = function(state) {
+  const start = state.pos
+  let ch = 0
+  state.lastIntValue = 0
+  while (isDecimalDigit(ch = state.current())) {
+    state.lastIntValue = 10 * state.lastIntValue + (ch - 0x30 /* 0 */)
+    state.advance()
+  }
+  return state.pos !== start
+}
+function isDecimalDigit(ch) {
+  return ch >= 0x30 /* 0 */ && ch <= 0x39 /* 9 */
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-HexDigits
+pp.regexp_eatHexDigits = function(state) {
+  const start = state.pos
+  let ch = 0
+  state.lastIntValue = 0
+  while (isHexDigit(ch = state.current())) {
+    state.lastIntValue = 16 * state.lastIntValue + hexToInt(ch)
+    state.advance()
+  }
+  return state.pos !== start
+}
+function isHexDigit(ch) {
+  return (
+    (ch >= 0x30 /* 0 */ && ch <= 0x39 /* 9 */) ||
+    (ch >= 0x41 /* A */ && ch <= 0x46 /* F */) ||
+    (ch >= 0x61 /* a */ && ch <= 0x66 /* f */)
+  )
+}
+function hexToInt(ch) {
+  if (ch >= 0x41 /* A */ && ch <= 0x46 /* F */) {
+    return 10 + (ch - 0x41 /* A */)
+  }
+  if (ch >= 0x61 /* a */ && ch <= 0x66 /* f */) {
+    return 10 + (ch - 0x61 /* a */)
+  }
+  return ch - 0x30 /* 0 */
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-LegacyOctalEscapeSequence
+// Allows only 0-377(octal) i.e. 0-255(decimal).
+pp.regexp_eatLegacyOctalEscapeSequence = function(state) {
+  if (this.regexp_eatOctalDigit(state)) {
+    const n1 = state.lastIntValue
+    if (this.regexp_eatOctalDigit(state)) {
+      const n2 = state.lastIntValue
+      if (n1 <= 3 && this.regexp_eatOctalDigit(state)) {
+        state.lastIntValue = n1 * 64 + n2 * 8 + state.lastIntValue
+      } else {
+        state.lastIntValue = n1 * 8 + n2
+      }
+    } else {
+      state.lastIntValue = n1
+    }
+    return true
+  }
+  return false
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-OctalDigit
+pp.regexp_eatOctalDigit = function(state) {
+  const ch = state.current()
+  if (isOctalDigit(ch)) {
+    state.lastIntValue = ch - 0x30 /* 0 */
+    state.advance()
+    return true
+  }
+  state.lastIntValue = 0
+  return false
+}
+function isOctalDigit(ch) {
+  return ch >= 0x30 /* 0 */ && ch <= 0x37 /* 7 */
+}
+
+// https://www.ecma-international.org/ecma-262/8.0/#prod-Hex4Digits
+// https://www.ecma-international.org/ecma-262/8.0/#prod-HexDigit
+// And HexDigit HexDigit in https://www.ecma-international.org/ecma-262/8.0/#prod-HexEscapeSequence
+pp.regexp_eatFixedHexDigits = function(state, length) {
+  const start = state.pos
+  state.lastIntValue = 0
+  for (let i = 0; i < length; ++i) {
+    const ch = state.current()
+    if (!isHexDigit(ch)) {
+      state.pos = start
+      return false
+    }
+    state.lastIntValue = 16 * state.lastIntValue + hexToInt(ch)
+    state.advance()
+  }
+  return true
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/scope.js b/tools/tests/apps/modules/imports/links/acorn/src/scope.js
new file mode 100644
index 0000000000..eab0002c04
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/scope.js
@@ -0,0 +1,74 @@
+import {Parser} from "./state"
+import {has} from "./util"
+
+const pp = Parser.prototype
+
+// Object.assign polyfill
+const assign = Object.assign || function(target, ...sources) {
+  for (let source of sources) {
+    for (const key in source) {
+      if (has(source, key)) {
+        target[key] = source[key]
+      }
+    }
+  }
+  return target
+}
+
+// The functions in this module keep track of declared variables in the current scope in order to detect duplicate variable names.
+
+pp.enterFunctionScope = function() {
+  // var: a hash of var-declared names in the current lexical scope
+  // lexical: a hash of lexically-declared names in the current lexical scope
+  // childVar: a hash of var-declared names in all child lexical scopes of the current lexical scope (within the current function scope)
+  // parentLexical: a hash of lexically-declared names in all parent lexical scopes of the current lexical scope (within the current function scope)
+  this.scopeStack.push({var: {}, lexical: {}, childVar: {}, parentLexical: {}})
+}
+
+pp.exitFunctionScope = function() {
+  this.scopeStack.pop()
+}
+
+pp.enterLexicalScope = function() {
+  const parentScope = this.scopeStack[this.scopeStack.length - 1]
+  const childScope = {var: {}, lexical: {}, childVar: {}, parentLexical: {}}
+
+  this.scopeStack.push(childScope)
+  assign(childScope.parentLexical, parentScope.lexical, parentScope.parentLexical)
+}
+
+pp.exitLexicalScope = function() {
+  const childScope = this.scopeStack.pop()
+  const parentScope = this.scopeStack[this.scopeStack.length - 1]
+
+  assign(parentScope.childVar, childScope.var, childScope.childVar)
+}
+
+/**
+ * A name can be declared with `var` if there are no variables with the same name declared with `let`/`const`
+ * in the current lexical scope or any of the parent lexical scopes in this function.
+ */
+pp.canDeclareVarName = function(name) {
+  const currentScope = this.scopeStack[this.scopeStack.length - 1]
+
+  return !has(currentScope.lexical, name) && !has(currentScope.parentLexical, name)
+}
+
+/**
+ * A name can be declared with `let`/`const` if there are no variables with the same name declared with `let`/`const`
+ * in the current scope, and there are no variables with the same name declared with `var` in the current scope or in
+ * any child lexical scopes in this function.
+ */
+pp.canDeclareLexicalName = function(name) {
+  const currentScope = this.scopeStack[this.scopeStack.length - 1]
+
+  return !has(currentScope.lexical, name) && !has(currentScope.var, name) && !has(currentScope.childVar, name)
+}
+
+pp.declareVarName = function(name) {
+  this.scopeStack[this.scopeStack.length - 1].var[name] = true
+}
+
+pp.declareLexicalName = function(name) {
+  this.scopeStack[this.scopeStack.length - 1].lexical[name] = true
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/state.js b/tools/tests/apps/modules/imports/links/acorn/src/state.js
new file mode 100644
index 0000000000..185fe28648
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/state.js
@@ -0,0 +1,118 @@
+import {reservedWords, keywords} from "./identifier"
+import {types as tt} from "./tokentype"
+import {lineBreak} from "./whitespace"
+import {getOptions} from "./options"
+
+// Registered plugins
+export const plugins = {}
+
+function keywordRegexp(words) {
+  return new RegExp("^(?:" + words.replace(/ /g, "|") + ")$")
+}
+
+export class Parser {
+  constructor(options, input, startPos) {
+    this.options = options = getOptions(options)
+    this.sourceFile = options.sourceFile
+    this.keywords = keywordRegexp(keywords[options.ecmaVersion >= 6 ? 6 : 5])
+    let reserved = ""
+    if (!options.allowReserved) {
+      for (let v = options.ecmaVersion;; v--)
+        if (reserved = reservedWords[v]) break
+      if (options.sourceType == "module") reserved += " await"
+    }
+    this.reservedWords = keywordRegexp(reserved)
+    let reservedStrict = (reserved ? reserved + " " : "") + reservedWords.strict
+    this.reservedWordsStrict = keywordRegexp(reservedStrict)
+    this.reservedWordsStrictBind = keywordRegexp(reservedStrict + " " + reservedWords.strictBind)
+    this.input = String(input)
+
+    // Used to signal to callers of `readWord1` whether the word
+    // contained any escape sequences. This is needed because words with
+    // escape sequences must not be interpreted as keywords.
+    this.containsEsc = false
+
+    // Load plugins
+    this.loadPlugins(options.plugins)
+
+    // Set up token state
+
+    // The current position of the tokenizer in the input.
+    if (startPos) {
+      this.pos = startPos
+      this.lineStart = this.input.lastIndexOf("\n", startPos - 1) + 1
+      this.curLine = this.input.slice(0, this.lineStart).split(lineBreak).length
+    } else {
+      this.pos = this.lineStart = 0
+      this.curLine = 1
+    }
+
+    // Properties of the current token:
+    // Its type
+    this.type = tt.eof
+    // For tokens that include more information than their type, the value
+    this.value = null
+    // Its start and end offset
+    this.start = this.end = this.pos
+    // And, if locations are used, the {line, column} object
+    // corresponding to those offsets
+    this.startLoc = this.endLoc = this.curPosition()
+
+    // Position information for the previous token
+    this.lastTokEndLoc = this.lastTokStartLoc = null
+    this.lastTokStart = this.lastTokEnd = this.pos
+
+    // The context stack is used to superficially track syntactic
+    // context to predict whether a regular expression is allowed in a
+    // given position.
+    this.context = this.initialContext()
+    this.exprAllowed = true
+
+    // Figure out if it's a module code.
+    this.inModule = options.sourceType === "module"
+    this.strict = this.inModule || this.strictDirective(this.pos)
+
+    // Used to signify the start of a potential arrow function
+    this.potentialArrowAt = -1
+
+    // Flags to track whether we are in a function, a generator, an async function.
+    this.inFunction = this.inGenerator = this.inAsync = false
+    // Positions to delayed-check that yield/await does not exist in default parameters.
+    this.yieldPos = this.awaitPos = 0
+    // Labels in scope.
+    this.labels = []
+
+    // If enabled, skip leading hashbang line.
+    if (this.pos === 0 && options.allowHashBang && this.input.slice(0, 2) === "#!")
+      this.skipLineComment(2)
+
+    // Scope tracking for duplicate variable names (see scope.js)
+    this.scopeStack = []
+    this.enterFunctionScope()
+
+    // For RegExp validation
+    this.regexpState = null
+  }
+
+  // DEPRECATED Kept for backwards compatibility until 3.0 in case a plugin uses them
+  isKeyword(word) { return this.keywords.test(word) }
+  isReservedWord(word) { return this.reservedWords.test(word) }
+
+  extend(name, f) {
+    this[name] = f(this[name])
+  }
+
+  loadPlugins(pluginConfigs) {
+    for (let name in pluginConfigs) {
+      let plugin = plugins[name]
+      if (!plugin) throw new Error("Plugin '" + name + "' not found")
+      plugin(this, pluginConfigs[name])
+    }
+  }
+
+  parse() {
+    let node = this.options.program || this.startNode()
+    this.nextToken()
+    return this.parseTopLevel(node)
+  }
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/statement.js b/tools/tests/apps/modules/imports/links/acorn/src/statement.js
new file mode 100644
index 0000000000..2612125df3
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/statement.js
@@ -0,0 +1,810 @@
+import {types as tt} from "./tokentype"
+import {Parser} from "./state"
+import {lineBreak, skipWhiteSpace} from "./whitespace"
+import {isIdentifierStart, isIdentifierChar, keywordRelationalOperator} from "./identifier"
+import {has} from "./util"
+import {DestructuringErrors} from "./parseutil"
+
+const pp = Parser.prototype
+
+// ### Statement parsing
+
+// Parse a program. Initializes the parser, reads any number of
+// statements, and wraps them in a Program node.  Optionally takes a
+// `program` argument.  If present, the statements will be appended
+// to its body instead of creating a new node.
+
+pp.parseTopLevel = function(node) {
+  let exports = {}
+  if (!node.body) node.body = []
+  while (this.type !== tt.eof) {
+    let stmt = this.parseStatement(true, true, exports)
+    node.body.push(stmt)
+  }
+  this.adaptDirectivePrologue(node.body)
+  this.next()
+  if (this.options.ecmaVersion >= 6) {
+    node.sourceType = this.options.sourceType
+  }
+  return this.finishNode(node, "Program")
+}
+
+const loopLabel = {kind: "loop"}, switchLabel = {kind: "switch"}
+
+pp.isLet = function() {
+  if (this.options.ecmaVersion < 6 || !this.isContextual("let")) return false
+  skipWhiteSpace.lastIndex = this.pos
+  let skip = skipWhiteSpace.exec(this.input)
+  let next = this.pos + skip[0].length, nextCh = this.input.charCodeAt(next)
+  if (nextCh === 91 || nextCh == 123) return true // '{' and '['
+  if (isIdentifierStart(nextCh, true)) {
+    let pos = next + 1
+    while (isIdentifierChar(this.input.charCodeAt(pos), true)) ++pos
+    let ident = this.input.slice(next, pos)
+    if (!keywordRelationalOperator.test(ident)) return true
+  }
+  return false
+}
+
+// check 'async [no LineTerminator here] function'
+// - 'async /*foo*/ function' is OK.
+// - 'async /*\n*/ function' is invalid.
+pp.isAsyncFunction = function() {
+  if (this.options.ecmaVersion < 8 || !this.isContextual("async"))
+    return false
+
+  skipWhiteSpace.lastIndex = this.pos
+  let skip = skipWhiteSpace.exec(this.input)
+  let next = this.pos + skip[0].length
+  return !lineBreak.test(this.input.slice(this.pos, next)) &&
+    this.input.slice(next, next + 8) === "function" &&
+    (next + 8 == this.input.length || !isIdentifierChar(this.input.charAt(next + 8)))
+}
+
+// Parse a single statement.
+//
+// If expecting a statement and finding a slash operator, parse a
+// regular expression literal. This is to handle cases like
+// `if (foo) /blah/.exec(foo)`, where looking at the previous token
+// does not help.
+
+pp.parseStatement = function(declaration, topLevel, exports) {
+  let starttype = this.type, node = this.startNode(), kind
+
+  if (this.isLet()) {
+    starttype = tt._var
+    kind = "let"
+  }
+
+  // Most types of statements are recognized by the keyword they
+  // start with. Many are trivial to parse, some require a bit of
+  // complexity.
+
+  switch (starttype) {
+  case tt._break: case tt._continue: return this.parseBreakContinueStatement(node, starttype.keyword)
+  case tt._debugger: return this.parseDebuggerStatement(node)
+  case tt._do: return this.parseDoStatement(node)
+  case tt._for: return this.parseForStatement(node)
+  case tt._function:
+    if (!declaration && this.options.ecmaVersion >= 6) this.unexpected()
+    return this.parseFunctionStatement(node, false)
+  case tt._class:
+    if (!declaration) this.unexpected()
+    return this.parseClass(node, true)
+  case tt._if: return this.parseIfStatement(node)
+  case tt._return: return this.parseReturnStatement(node)
+  case tt._switch: return this.parseSwitchStatement(node)
+  case tt._throw: return this.parseThrowStatement(node)
+  case tt._try: return this.parseTryStatement(node)
+  case tt._const: case tt._var:
+    kind = kind || this.value
+    if (!declaration && kind != "var") this.unexpected()
+    return this.parseVarStatement(node, kind)
+  case tt._while: return this.parseWhileStatement(node)
+  case tt._with: return this.parseWithStatement(node)
+  case tt.braceL: return this.parseBlock()
+  case tt.semi: return this.parseEmptyStatement(node)
+  case tt._export:
+  case tt._import:
+    if (!this.options.allowImportExportEverywhere) {
+      if (!topLevel)
+        this.raise(this.start, "'import' and 'export' may only appear at the top level")
+      if (!this.inModule)
+        this.raise(this.start, "'import' and 'export' may appear only with 'sourceType: module'")
+    }
+    return starttype === tt._import ? this.parseImport(node) : this.parseExport(node, exports)
+
+    // If the statement does not start with a statement keyword or a
+    // brace, it's an ExpressionStatement or LabeledStatement. We
+    // simply start parsing an expression, and afterwards, if the
+    // next token is a colon and the expression was a simple
+    // Identifier node, we switch to interpreting it as a label.
+  default:
+    if (this.isAsyncFunction()) {
+      if (!declaration) this.unexpected()
+      this.next()
+      return this.parseFunctionStatement(node, true)
+    }
+
+    let maybeName = this.value, expr = this.parseExpression()
+    if (starttype === tt.name && expr.type === "Identifier" && this.eat(tt.colon))
+      return this.parseLabeledStatement(node, maybeName, expr)
+    else return this.parseExpressionStatement(node, expr)
+  }
+}
+
+pp.parseBreakContinueStatement = function(node, keyword) {
+  let isBreak = keyword == "break"
+  this.next()
+  if (this.eat(tt.semi) || this.insertSemicolon()) node.label = null
+  else if (this.type !== tt.name) this.unexpected()
+  else {
+    node.label = this.parseIdent()
+    this.semicolon()
+  }
+
+  // Verify that there is an actual destination to break or
+  // continue to.
+  let i = 0
+  for (; i < this.labels.length; ++i) {
+    let lab = this.labels[i]
+    if (node.label == null || lab.name === node.label.name) {
+      if (lab.kind != null && (isBreak || lab.kind === "loop")) break
+      if (node.label && isBreak) break
+    }
+  }
+  if (i === this.labels.length) this.raise(node.start, "Unsyntactic " + keyword)
+  return this.finishNode(node, isBreak ? "BreakStatement" : "ContinueStatement")
+}
+
+pp.parseDebuggerStatement = function(node) {
+  this.next()
+  this.semicolon()
+  return this.finishNode(node, "DebuggerStatement")
+}
+
+pp.parseDoStatement = function(node) {
+  this.next()
+  this.labels.push(loopLabel)
+  node.body = this.parseStatement(false)
+  this.labels.pop()
+  this.expect(tt._while)
+  node.test = this.parseParenExpression()
+  if (this.options.ecmaVersion >= 6)
+    this.eat(tt.semi)
+  else
+    this.semicolon()
+  return this.finishNode(node, "DoWhileStatement")
+}
+
+// Disambiguating between a `for` and a `for`/`in` or `for`/`of`
+// loop is non-trivial. Basically, we have to parse the init `var`
+// statement or expression, disallowing the `in` operator (see
+// the second parameter to `parseExpression`), and then check
+// whether the next token is `in` or `of`. When there is no init
+// part (semicolon immediately after the opening parenthesis), it
+// is a regular `for` loop.
+
+pp.parseForStatement = function(node) {
+  this.next()
+  let awaitAt = (this.options.ecmaVersion >= 9 && this.inAsync && this.eatContextual("await")) ? this.lastTokStart : -1
+  this.labels.push(loopLabel)
+  this.enterLexicalScope()
+  this.expect(tt.parenL)
+  if (this.type === tt.semi) {
+    if (awaitAt > -1) this.unexpected(awaitAt)
+    return this.parseFor(node, null)
+  }
+  let isLet = this.isLet()
+  if (this.type === tt._var || this.type === tt._const || isLet) {
+    let init = this.startNode(), kind = isLet ? "let" : this.value
+    this.next()
+    this.parseVar(init, true, kind)
+    this.finishNode(init, "VariableDeclaration")
+    if ((this.type === tt._in || (this.options.ecmaVersion >= 6 && this.isContextual("of"))) && init.declarations.length === 1 &&
+        !(kind !== "var" && init.declarations[0].init)) {
+      if (this.options.ecmaVersion >= 9) {
+        if (this.type === tt._in) {
+          if (awaitAt > -1) this.unexpected(awaitAt)
+        } else node.await = awaitAt > -1
+      }
+      return this.parseForIn(node, init)
+    }
+    if (awaitAt > -1) this.unexpected(awaitAt)
+    return this.parseFor(node, init)
+  }
+  let refDestructuringErrors = new DestructuringErrors
+  let init = this.parseExpression(true, refDestructuringErrors)
+  if (this.type === tt._in || (this.options.ecmaVersion >= 6 && this.isContextual("of"))) {
+    if (this.options.ecmaVersion >= 9) {
+      if (this.type === tt._in) {
+        if (awaitAt > -1) this.unexpected(awaitAt)
+      } else node.await = awaitAt > -1
+    }
+    this.toAssignable(init, false, refDestructuringErrors)
+    this.checkLVal(init)
+    return this.parseForIn(node, init)
+  } else {
+    this.checkExpressionErrors(refDestructuringErrors, true)
+  }
+  if (awaitAt > -1) this.unexpected(awaitAt)
+  return this.parseFor(node, init)
+}
+
+pp.parseFunctionStatement = function(node, isAsync) {
+  this.next()
+  return this.parseFunction(node, true, false, isAsync)
+}
+
+pp.parseIfStatement = function(node) {
+  this.next()
+  node.test = this.parseParenExpression()
+  // allow function declarations in branches, but only in non-strict mode
+  node.consequent = this.parseStatement(!this.strict && this.type == tt._function)
+  node.alternate = this.eat(tt._else) ? this.parseStatement(!this.strict && this.type == tt._function) : null
+  return this.finishNode(node, "IfStatement")
+}
+
+pp.parseReturnStatement = function(node) {
+  if (!this.inFunction && !this.options.allowReturnOutsideFunction)
+    this.raise(this.start, "'return' outside of function")
+  this.next()
+
+  // In `return` (and `break`/`continue`), the keywords with
+  // optional arguments, we eagerly look for a semicolon or the
+  // possibility to insert one.
+
+  if (this.eat(tt.semi) || this.insertSemicolon()) node.argument = null
+  else { node.argument = this.parseExpression(); this.semicolon() }
+  return this.finishNode(node, "ReturnStatement")
+}
+
+pp.parseSwitchStatement = function(node) {
+  this.next()
+  node.discriminant = this.parseParenExpression()
+  node.cases = []
+  this.expect(tt.braceL)
+  this.labels.push(switchLabel)
+  this.enterLexicalScope()
+
+  // Statements under must be grouped (by label) in SwitchCase
+  // nodes. `cur` is used to keep the node that we are currently
+  // adding statements to.
+
+  let cur
+  for (let sawDefault = false; this.type != tt.braceR;) {
+    if (this.type === tt._case || this.type === tt._default) {
+      let isCase = this.type === tt._case
+      if (cur) this.finishNode(cur, "SwitchCase")
+      node.cases.push(cur = this.startNode())
+      cur.consequent = []
+      this.next()
+      if (isCase) {
+        cur.test = this.parseExpression()
+      } else {
+        if (sawDefault) this.raiseRecoverable(this.lastTokStart, "Multiple default clauses")
+        sawDefault = true
+        cur.test = null
+      }
+      this.expect(tt.colon)
+    } else {
+      if (!cur) this.unexpected()
+      cur.consequent.push(this.parseStatement(true))
+    }
+  }
+  this.exitLexicalScope()
+  if (cur) this.finishNode(cur, "SwitchCase")
+  this.next() // Closing brace
+  this.labels.pop()
+  return this.finishNode(node, "SwitchStatement")
+}
+
+pp.parseThrowStatement = function(node) {
+  this.next()
+  if (lineBreak.test(this.input.slice(this.lastTokEnd, this.start)))
+    this.raise(this.lastTokEnd, "Illegal newline after throw")
+  node.argument = this.parseExpression()
+  this.semicolon()
+  return this.finishNode(node, "ThrowStatement")
+}
+
+// Reused empty array added for node fields that are always empty.
+
+const empty = []
+
+pp.parseTryStatement = function(node) {
+  this.next()
+  node.block = this.parseBlock()
+  node.handler = null
+  if (this.type === tt._catch) {
+    let clause = this.startNode()
+    this.next()
+    this.expect(tt.parenL)
+    clause.param = this.parseBindingAtom()
+    this.enterLexicalScope()
+    this.checkLVal(clause.param, "let")
+    this.expect(tt.parenR)
+    clause.body = this.parseBlock(false)
+    this.exitLexicalScope()
+    node.handler = this.finishNode(clause, "CatchClause")
+  }
+  node.finalizer = this.eat(tt._finally) ? this.parseBlock() : null
+  if (!node.handler && !node.finalizer)
+    this.raise(node.start, "Missing catch or finally clause")
+  return this.finishNode(node, "TryStatement")
+}
+
+pp.parseVarStatement = function(node, kind) {
+  this.next()
+  this.parseVar(node, false, kind)
+  this.semicolon()
+  return this.finishNode(node, "VariableDeclaration")
+}
+
+pp.parseWhileStatement = function(node) {
+  this.next()
+  node.test = this.parseParenExpression()
+  this.labels.push(loopLabel)
+  node.body = this.parseStatement(false)
+  this.labels.pop()
+  return this.finishNode(node, "WhileStatement")
+}
+
+pp.parseWithStatement = function(node) {
+  if (this.strict) this.raise(this.start, "'with' in strict mode")
+  this.next()
+  node.object = this.parseParenExpression()
+  node.body = this.parseStatement(false)
+  return this.finishNode(node, "WithStatement")
+}
+
+pp.parseEmptyStatement = function(node) {
+  this.next()
+  return this.finishNode(node, "EmptyStatement")
+}
+
+pp.parseLabeledStatement = function(node, maybeName, expr) {
+  for (let label of this.labels)
+    if (label.name === maybeName)
+      this.raise(expr.start, "Label '" + maybeName + "' is already declared")
+  let kind = this.type.isLoop ? "loop" : this.type === tt._switch ? "switch" : null
+  for (let i = this.labels.length - 1; i >= 0; i--) {
+    let label = this.labels[i]
+    if (label.statementStart == node.start) {
+      // Update information about previous labels on this node
+      label.statementStart = this.start
+      label.kind = kind
+    } else break
+  }
+  this.labels.push({name: maybeName, kind, statementStart: this.start})
+  node.body = this.parseStatement(true)
+  if (node.body.type == "ClassDeclaration" ||
+      node.body.type == "VariableDeclaration" && node.body.kind != "var" ||
+      node.body.type == "FunctionDeclaration" && (this.strict || node.body.generator))
+    this.raiseRecoverable(node.body.start, "Invalid labeled declaration")
+  this.labels.pop()
+  node.label = expr
+  return this.finishNode(node, "LabeledStatement")
+}
+
+pp.parseExpressionStatement = function(node, expr) {
+  node.expression = expr
+  this.semicolon()
+  return this.finishNode(node, "ExpressionStatement")
+}
+
+// Parse a semicolon-enclosed block of statements, handling `"use
+// strict"` declarations when `allowStrict` is true (used for
+// function bodies).
+
+pp.parseBlock = function(createNewLexicalScope = true) {
+  let node = this.startNode()
+  node.body = []
+  this.expect(tt.braceL)
+  if (createNewLexicalScope) {
+    this.enterLexicalScope()
+  }
+  while (!this.eat(tt.braceR)) {
+    let stmt = this.parseStatement(true)
+    node.body.push(stmt)
+  }
+  if (createNewLexicalScope) {
+    this.exitLexicalScope()
+  }
+  return this.finishNode(node, "BlockStatement")
+}
+
+// Parse a regular `for` loop. The disambiguation code in
+// `parseStatement` will already have parsed the init statement or
+// expression.
+
+pp.parseFor = function(node, init) {
+  node.init = init
+  this.expect(tt.semi)
+  node.test = this.type === tt.semi ? null : this.parseExpression()
+  this.expect(tt.semi)
+  node.update = this.type === tt.parenR ? null : this.parseExpression()
+  this.expect(tt.parenR)
+  this.exitLexicalScope()
+  node.body = this.parseStatement(false)
+  this.labels.pop()
+  return this.finishNode(node, "ForStatement")
+}
+
+// Parse a `for`/`in` and `for`/`of` loop, which are almost
+// same from parser's perspective.
+
+pp.parseForIn = function(node, init) {
+  let type = this.type === tt._in ? "ForInStatement" : "ForOfStatement"
+  this.next()
+  if (type == "ForInStatement") {
+    if (init.type === "AssignmentPattern" ||
+      (init.type === "VariableDeclaration" && init.declarations[0].init != null &&
+       (this.strict || init.declarations[0].id.type !== "Identifier")))
+      this.raise(init.start, "Invalid assignment in for-in loop head")
+  }
+  node.left = init
+  node.right = type == "ForInStatement" ? this.parseExpression() : this.parseMaybeAssign()
+  this.expect(tt.parenR)
+  this.exitLexicalScope()
+  node.body = this.parseStatement(false)
+  this.labels.pop()
+  return this.finishNode(node, type)
+}
+
+// Parse a list of variable declarations.
+
+pp.parseVar = function(node, isFor, kind) {
+  node.declarations = []
+  node.kind = kind
+  for (;;) {
+    let decl = this.startNode()
+    this.parseVarId(decl, kind)
+    if (this.eat(tt.eq)) {
+      decl.init = this.parseMaybeAssign(isFor)
+    } else if (kind === "const" && !(this.type === tt._in || (this.options.ecmaVersion >= 6 && this.isContextual("of")))) {
+      this.unexpected()
+    } else if (decl.id.type != "Identifier" && !(isFor && (this.type === tt._in || this.isContextual("of")))) {
+      this.raise(this.lastTokEnd, "Complex binding patterns require an initialization value")
+    } else {
+      decl.init = null
+    }
+    node.declarations.push(this.finishNode(decl, "VariableDeclarator"))
+    if (!this.eat(tt.comma)) break
+  }
+  return node
+}
+
+pp.parseVarId = function(decl, kind) {
+  decl.id = this.parseBindingAtom(kind)
+  this.checkLVal(decl.id, kind, false)
+}
+
+// Parse a function declaration or literal (depending on the
+// `isStatement` parameter).
+
+pp.parseFunction = function(node, isStatement, allowExpressionBody, isAsync) {
+  this.initFunction(node)
+  if (this.options.ecmaVersion >= 9 || this.options.ecmaVersion >= 6 && !isAsync)
+    node.generator = this.eat(tt.star)
+  if (this.options.ecmaVersion >= 8)
+    node.async = !!isAsync
+
+  if (isStatement) {
+    node.id = isStatement === "nullableID" && this.type != tt.name ? null : this.parseIdent()
+    if (node.id) {
+      this.checkLVal(node.id, "var")
+    }
+  }
+
+  let oldInGen = this.inGenerator, oldInAsync = this.inAsync,
+      oldYieldPos = this.yieldPos, oldAwaitPos = this.awaitPos, oldInFunc = this.inFunction
+  this.inGenerator = node.generator
+  this.inAsync = node.async
+  this.yieldPos = 0
+  this.awaitPos = 0
+  this.inFunction = true
+  this.enterFunctionScope()
+
+  if (!isStatement)
+    node.id = this.type == tt.name ? this.parseIdent() : null
+
+  this.parseFunctionParams(node)
+  this.parseFunctionBody(node, allowExpressionBody)
+
+  this.inGenerator = oldInGen
+  this.inAsync = oldInAsync
+  this.yieldPos = oldYieldPos
+  this.awaitPos = oldAwaitPos
+  this.inFunction = oldInFunc
+  return this.finishNode(node, isStatement ? "FunctionDeclaration" : "FunctionExpression")
+}
+
+pp.parseFunctionParams = function(node) {
+  this.expect(tt.parenL)
+  node.params = this.parseBindingList(tt.parenR, false, this.options.ecmaVersion >= 8)
+  this.checkYieldAwaitInDefaultParams()
+}
+
+// Parse a class declaration or literal (depending on the
+// `isStatement` parameter).
+
+pp.parseClass = function(node, isStatement) {
+  this.next()
+
+  this.parseClassId(node, isStatement)
+  this.parseClassSuper(node)
+  let classBody = this.startNode()
+  let hadConstructor = false
+  classBody.body = []
+  this.expect(tt.braceL)
+  while (!this.eat(tt.braceR)) {
+    const member = this.parseClassMember(classBody)
+    if (member && member.type === "MethodDefinition" && member.kind === "constructor") {
+      if (hadConstructor) this.raise(member.start, "Duplicate constructor in the same class")
+      hadConstructor = true
+    }
+  }
+  node.body = this.finishNode(classBody, "ClassBody")
+  return this.finishNode(node, isStatement ? "ClassDeclaration" : "ClassExpression")
+}
+
+pp.parseClassMember = function(classBody) {
+  if (this.eat(tt.semi)) return null
+
+  let method = this.startNode()
+  const tryContextual = (k, noLineBreak = false) => {
+    const start = this.start, startLoc = this.startLoc
+    if (!this.eatContextual(k)) return false
+    if (this.type !== tt.parenL && (!noLineBreak || !this.canInsertSemicolon())) return true
+    if (method.key) this.unexpected()
+    method.computed = false
+    method.key = this.startNodeAt(start, startLoc)
+    method.key.name = k
+    this.finishNode(method.key, "Identifier")
+    return false
+  }
+
+  method.kind = "method"
+  method.static = tryContextual("static")
+  let isGenerator = this.eat(tt.star)
+  let isAsync = false
+  if (!isGenerator) {
+    if (this.options.ecmaVersion >= 8 && tryContextual("async", true)) {
+      isAsync = true
+      isGenerator = this.options.ecmaVersion >= 9 && this.eat(tt.star)
+    } else if (tryContextual("get")) {
+      method.kind = "get"
+    } else if (tryContextual("set")) {
+      method.kind = "set"
+    }
+  }
+  if (!method.key) this.parsePropertyName(method)
+  let {key} = method
+  if (!method.computed && !method.static && (key.type === "Identifier" && key.name === "constructor" ||
+      key.type === "Literal" && key.value === "constructor")) {
+    if (method.kind !== "method") this.raise(key.start, "Constructor can't have get/set modifier")
+    if (isGenerator) this.raise(key.start, "Constructor can't be a generator")
+    if (isAsync) this.raise(key.start, "Constructor can't be an async method")
+    method.kind = "constructor"
+  } else if (method.static && key.type === "Identifier" && key.name === "prototype") {
+    this.raise(key.start, "Classes may not have a static property named prototype")
+  }
+  this.parseClassMethod(classBody, method, isGenerator, isAsync)
+  if (method.kind === "get" && method.value.params.length !== 0)
+    this.raiseRecoverable(method.value.start, "getter should have no params")
+  if (method.kind === "set" && method.value.params.length !== 1)
+    this.raiseRecoverable(method.value.start, "setter should have exactly one param")
+  if (method.kind === "set" && method.value.params[0].type === "RestElement")
+    this.raiseRecoverable(method.value.params[0].start, "Setter cannot use rest params")
+  return method
+}
+
+pp.parseClassMethod = function(classBody, method, isGenerator, isAsync) {
+  method.value = this.parseMethod(isGenerator, isAsync)
+  classBody.body.push(this.finishNode(method, "MethodDefinition"))
+}
+
+pp.parseClassId = function(node, isStatement) {
+  node.id = this.type === tt.name ? this.parseIdent() : isStatement === true ? this.unexpected() : null
+}
+
+pp.parseClassSuper = function(node) {
+  node.superClass = this.eat(tt._extends) ? this.parseExprSubscripts() : null
+}
+
+// Parses module export declaration.
+
+pp.parseExport = function(node, exports) {
+  this.next()
+  // export * from '...'
+  if (this.eat(tt.star)) {
+    this.expectContextual("from")
+    if (this.type !== tt.string) this.unexpected()
+    node.source = this.parseExprAtom()
+    this.semicolon()
+    return this.finishNode(node, "ExportAllDeclaration")
+  }
+  if (this.eat(tt._default)) { // export default ...
+    this.checkExport(exports, "default", this.lastTokStart)
+    let isAsync
+    if (this.type === tt._function || (isAsync = this.isAsyncFunction())) {
+      let fNode = this.startNode()
+      this.next()
+      if (isAsync) this.next()
+      node.declaration = this.parseFunction(fNode, "nullableID", false, isAsync)
+    } else if (this.type === tt._class) {
+      let cNode = this.startNode()
+      node.declaration = this.parseClass(cNode, "nullableID")
+    } else {
+      node.declaration = this.parseMaybeAssign()
+      this.semicolon()
+    }
+    return this.finishNode(node, "ExportDefaultDeclaration")
+  }
+  // export var|const|let|function|class ...
+  if (this.shouldParseExportStatement()) {
+    node.declaration = this.parseStatement(true)
+    if (node.declaration.type === "VariableDeclaration")
+      this.checkVariableExport(exports, node.declaration.declarations)
+    else
+      this.checkExport(exports, node.declaration.id.name, node.declaration.id.start)
+    node.specifiers = []
+    node.source = null
+  } else { // export { x, y as z } [from '...']
+    node.declaration = null
+    node.specifiers = this.parseExportSpecifiers(exports)
+    if (this.eatContextual("from")) {
+      if (this.type !== tt.string) this.unexpected()
+      node.source = this.parseExprAtom()
+    } else {
+      // check for keywords used as local names
+      for (let spec of node.specifiers) {
+        this.checkUnreserved(spec.local)
+      }
+
+      node.source = null
+    }
+    this.semicolon()
+  }
+  return this.finishNode(node, "ExportNamedDeclaration")
+}
+
+pp.checkExport = function(exports, name, pos) {
+  if (!exports) return
+  if (has(exports, name))
+    this.raiseRecoverable(pos, "Duplicate export '" + name + "'")
+  exports[name] = true
+}
+
+pp.checkPatternExport = function(exports, pat) {
+  let type = pat.type
+  if (type == "Identifier")
+    this.checkExport(exports, pat.name, pat.start)
+  else if (type == "ObjectPattern")
+    for (let prop of pat.properties)
+      this.checkPatternExport(exports, prop)
+  else if (type == "ArrayPattern")
+    for (let elt of pat.elements) {
+      if (elt) this.checkPatternExport(exports, elt)
+    }
+  else if (type == "Property")
+    this.checkPatternExport(exports, pat.value)
+  else if (type == "AssignmentPattern")
+    this.checkPatternExport(exports, pat.left)
+  else if (type == "RestElement")
+    this.checkPatternExport(exports, pat.argument)
+  else if (type == "ParenthesizedExpression")
+    this.checkPatternExport(exports, pat.expression)
+}
+
+pp.checkVariableExport = function(exports, decls) {
+  if (!exports) return
+  for (let decl of decls)
+    this.checkPatternExport(exports, decl.id)
+}
+
+pp.shouldParseExportStatement = function() {
+  return this.type.keyword === "var" ||
+    this.type.keyword === "const" ||
+    this.type.keyword === "class" ||
+    this.type.keyword === "function" ||
+    this.isLet() ||
+    this.isAsyncFunction()
+}
+
+// Parses a comma-separated list of module exports.
+
+pp.parseExportSpecifiers = function(exports) {
+  let nodes = [], first = true
+  // export { x, y as z } [from '...']
+  this.expect(tt.braceL)
+  while (!this.eat(tt.braceR)) {
+    if (!first) {
+      this.expect(tt.comma)
+      if (this.afterTrailingComma(tt.braceR)) break
+    } else first = false
+
+    let node = this.startNode()
+    node.local = this.parseIdent(true)
+    node.exported = this.eatContextual("as") ? this.parseIdent(true) : node.local
+    this.checkExport(exports, node.exported.name, node.exported.start)
+    nodes.push(this.finishNode(node, "ExportSpecifier"))
+  }
+  return nodes
+}
+
+// Parses import declaration.
+
+pp.parseImport = function(node) {
+  this.next()
+  // import '...'
+  if (this.type === tt.string) {
+    node.specifiers = empty
+    node.source = this.parseExprAtom()
+  } else {
+    node.specifiers = this.parseImportSpecifiers()
+    this.expectContextual("from")
+    node.source = this.type === tt.string ? this.parseExprAtom() : this.unexpected()
+  }
+  this.semicolon()
+  return this.finishNode(node, "ImportDeclaration")
+}
+
+// Parses a comma-separated list of module imports.
+
+pp.parseImportSpecifiers = function() {
+  let nodes = [], first = true
+  if (this.type === tt.name) {
+    // import defaultObj, { x, y as z } from '...'
+    let node = this.startNode()
+    node.local = this.parseIdent()
+    this.checkLVal(node.local, "let")
+    nodes.push(this.finishNode(node, "ImportDefaultSpecifier"))
+    if (!this.eat(tt.comma)) return nodes
+  }
+  if (this.type === tt.star) {
+    let node = this.startNode()
+    this.next()
+    this.expectContextual("as")
+    node.local = this.parseIdent()
+    this.checkLVal(node.local, "let")
+    nodes.push(this.finishNode(node, "ImportNamespaceSpecifier"))
+    return nodes
+  }
+  this.expect(tt.braceL)
+  while (!this.eat(tt.braceR)) {
+    if (!first) {
+      this.expect(tt.comma)
+      if (this.afterTrailingComma(tt.braceR)) break
+    } else first = false
+
+    let node = this.startNode()
+    node.imported = this.parseIdent(true)
+    if (this.eatContextual("as")) {
+      node.local = this.parseIdent()
+    } else {
+      this.checkUnreserved(node.imported)
+      node.local = node.imported
+    }
+    this.checkLVal(node.local, "let")
+    nodes.push(this.finishNode(node, "ImportSpecifier"))
+  }
+  return nodes
+}
+
+// Set `ExpressionStatement#directive` property for directive prologues.
+pp.adaptDirectivePrologue = function(statements) {
+  for (let i = 0; i < statements.length && this.isDirectiveCandidate(statements[i]); ++i) {
+    statements[i].directive = statements[i].expression.raw.slice(1, -1)
+  }
+}
+pp.isDirectiveCandidate = function(statement) {
+  return (
+    statement.type === "ExpressionStatement" &&
+    statement.expression.type === "Literal" &&
+    typeof statement.expression.value === "string" &&
+    // Reject parenthesized strings.
+    (this.input[statement.start] === "\"" || this.input[statement.start] === "'")
+  )
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/tokencontext.js b/tools/tests/apps/modules/imports/links/acorn/src/tokencontext.js
new file mode 100644
index 0000000000..18dda85ce6
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/tokencontext.js
@@ -0,0 +1,148 @@
+// The algorithm used to determine whether a regexp can appear at a
+// given point in the program is loosely based on sweet.js' approach.
+// See https://github.com/mozilla/sweet.js/wiki/design
+
+import {Parser} from "./state"
+import {types as tt} from "./tokentype"
+import {lineBreak} from "./whitespace"
+
+export class TokContext {
+  constructor(token, isExpr, preserveSpace, override, generator) {
+    this.token = token
+    this.isExpr = !!isExpr
+    this.preserveSpace = !!preserveSpace
+    this.override = override
+    this.generator = !!generator
+  }
+}
+
+export const types = {
+  b_stat: new TokContext("{", false),
+  b_expr: new TokContext("{", true),
+  b_tmpl: new TokContext("${", false),
+  p_stat: new TokContext("(", false),
+  p_expr: new TokContext("(", true),
+  q_tmpl: new TokContext("`", true, true, p => p.tryReadTemplateToken()),
+  f_stat: new TokContext("function", false),
+  f_expr: new TokContext("function", true),
+  f_expr_gen: new TokContext("function", true, false, null, true),
+  f_gen: new TokContext("function", false, false, null, true)
+}
+
+const pp = Parser.prototype
+
+pp.initialContext = function() {
+  return [types.b_stat]
+}
+
+pp.braceIsBlock = function(prevType) {
+  let parent = this.curContext()
+  if (parent === types.f_expr || parent === types.f_stat)
+    return true
+  if (prevType === tt.colon && (parent === types.b_stat || parent === types.b_expr))
+    return !parent.isExpr
+
+  // The check for `tt.name && exprAllowed` detects whether we are
+  // after a `yield` or `of` construct. See the `updateContext` for
+  // `tt.name`.
+  if (prevType === tt._return || prevType == tt.name && this.exprAllowed)
+    return lineBreak.test(this.input.slice(this.lastTokEnd, this.start))
+  if (prevType === tt._else || prevType === tt.semi || prevType === tt.eof || prevType === tt.parenR || prevType == tt.arrow)
+    return true
+  if (prevType == tt.braceL)
+    return parent === types.b_stat
+  if (prevType == tt._var || prevType == tt.name)
+    return false
+  return !this.exprAllowed
+}
+
+pp.inGeneratorContext = function() {
+  for (let i = this.context.length - 1; i >= 1; i--) {
+    let context = this.context[i]
+    if (context.token === "function")
+      return context.generator
+  }
+  return false
+}
+
+pp.updateContext = function(prevType) {
+  let update, type = this.type
+  if (type.keyword && prevType == tt.dot)
+    this.exprAllowed = false
+  else if (update = type.updateContext)
+    update.call(this, prevType)
+  else
+    this.exprAllowed = type.beforeExpr
+}
+
+// Token-specific context update code
+
+tt.parenR.updateContext = tt.braceR.updateContext = function() {
+  if (this.context.length == 1) {
+    this.exprAllowed = true
+    return
+  }
+  let out = this.context.pop()
+  if (out === types.b_stat && this.curContext().token === "function") {
+    out = this.context.pop()
+  }
+  this.exprAllowed = !out.isExpr
+}
+
+tt.braceL.updateContext = function(prevType) {
+  this.context.push(this.braceIsBlock(prevType) ? types.b_stat : types.b_expr)
+  this.exprAllowed = true
+}
+
+tt.dollarBraceL.updateContext = function() {
+  this.context.push(types.b_tmpl)
+  this.exprAllowed = true
+}
+
+tt.parenL.updateContext = function(prevType) {
+  let statementParens = prevType === tt._if || prevType === tt._for || prevType === tt._with || prevType === tt._while
+  this.context.push(statementParens ? types.p_stat : types.p_expr)
+  this.exprAllowed = true
+}
+
+tt.incDec.updateContext = function() {
+  // tokExprAllowed stays unchanged
+}
+
+tt._function.updateContext = tt._class.updateContext = function(prevType) {
+  if (prevType.beforeExpr && prevType !== tt.semi && prevType !== tt._else &&
+      !((prevType === tt.colon || prevType === tt.braceL) && this.curContext() === types.b_stat))
+    this.context.push(types.f_expr)
+  else
+    this.context.push(types.f_stat)
+  this.exprAllowed = false
+}
+
+tt.backQuote.updateContext = function() {
+  if (this.curContext() === types.q_tmpl)
+    this.context.pop()
+  else
+    this.context.push(types.q_tmpl)
+  this.exprAllowed = false
+}
+
+tt.star.updateContext = function(prevType) {
+  if (prevType == tt._function) {
+    let index = this.context.length - 1
+    if (this.context[index] === types.f_expr)
+      this.context[index] = types.f_expr_gen
+    else
+      this.context[index] = types.f_gen
+  }
+  this.exprAllowed = true
+}
+
+tt.name.updateContext = function(prevType) {
+  let allowed = false
+  if (this.options.ecmaVersion >= 6) {
+    if (this.value == "of" && !this.exprAllowed ||
+        this.value == "yield" && this.inGeneratorContext())
+      allowed = true
+  }
+  this.exprAllowed = allowed
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/tokenize.js b/tools/tests/apps/modules/imports/links/acorn/src/tokenize.js
new file mode 100644
index 0000000000..3afb8386f2
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/tokenize.js
@@ -0,0 +1,698 @@
+import {isIdentifierStart, isIdentifierChar} from "./identifier"
+import {types as tt, keywords as keywordTypes} from "./tokentype"
+import {Parser} from "./state"
+import {SourceLocation} from "./locutil"
+import {RegExpValidationState} from "./regexp"
+import {lineBreak, lineBreakG, isNewLine, nonASCIIwhitespace} from "./whitespace"
+
+// Object type used to represent tokens. Note that normally, tokens
+// simply exist as properties on the parser object. This is only
+// used for the onToken callback and the external tokenizer.
+
+export class Token {
+  constructor(p) {
+    this.type = p.type
+    this.value = p.value
+    this.start = p.start
+    this.end = p.end
+    if (p.options.locations)
+      this.loc = new SourceLocation(p, p.startLoc, p.endLoc)
+    if (p.options.ranges)
+      this.range = [p.start, p.end]
+  }
+}
+
+// ## Tokenizer
+
+const pp = Parser.prototype
+
+// Move to the next token
+
+pp.next = function() {
+  if (this.options.onToken)
+    this.options.onToken(new Token(this))
+
+  this.lastTokEnd = this.end
+  this.lastTokStart = this.start
+  this.lastTokEndLoc = this.endLoc
+  this.lastTokStartLoc = this.startLoc
+  this.nextToken()
+}
+
+pp.getToken = function() {
+  this.next()
+  return new Token(this)
+}
+
+// If we're in an ES6 environment, make parsers iterable
+if (typeof Symbol !== "undefined")
+  pp[Symbol.iterator] = function() {
+    return {
+      next: () => {
+        let token = this.getToken()
+        return {
+          done: token.type === tt.eof,
+          value: token
+        }
+      }
+    }
+  }
+
+// Toggle strict mode. Re-reads the next number or string to please
+// pedantic tests (`"use strict"; 010;` should fail).
+
+pp.curContext = function() {
+  return this.context[this.context.length - 1]
+}
+
+// Read a single token, updating the parser object's token-related
+// properties.
+
+pp.nextToken = function() {
+  let curContext = this.curContext()
+  if (!curContext || !curContext.preserveSpace) this.skipSpace()
+
+  this.start = this.pos
+  if (this.options.locations) this.startLoc = this.curPosition()
+  if (this.pos >= this.input.length) return this.finishToken(tt.eof)
+
+  if (curContext.override) return curContext.override(this)
+  else this.readToken(this.fullCharCodeAtPos())
+}
+
+pp.readToken = function(code) {
+  // Identifier or keyword. '\uXXXX' sequences are allowed in
+  // identifiers, so '\' also dispatches to that.
+  if (isIdentifierStart(code, this.options.ecmaVersion >= 6) || code === 92 /* '\' */)
+    return this.readWord()
+
+  return this.getTokenFromCode(code)
+}
+
+pp.fullCharCodeAtPos = function() {
+  let code = this.input.charCodeAt(this.pos)
+  if (code <= 0xd7ff || code >= 0xe000) return code
+  let next = this.input.charCodeAt(this.pos + 1)
+  return (code << 10) + next - 0x35fdc00
+}
+
+pp.skipBlockComment = function() {
+  let startLoc = this.options.onComment && this.curPosition()
+  let start = this.pos, end = this.input.indexOf("*/", this.pos += 2)
+  if (end === -1) this.raise(this.pos - 2, "Unterminated comment")
+  this.pos = end + 2
+  if (this.options.locations) {
+    lineBreakG.lastIndex = start
+    let match
+    while ((match = lineBreakG.exec(this.input)) && match.index < this.pos) {
+      ++this.curLine
+      this.lineStart = match.index + match[0].length
+    }
+  }
+  if (this.options.onComment)
+    this.options.onComment(true, this.input.slice(start + 2, end), start, this.pos,
+                           startLoc, this.curPosition())
+}
+
+pp.skipLineComment = function(startSkip) {
+  let start = this.pos
+  let startLoc = this.options.onComment && this.curPosition()
+  let ch = this.input.charCodeAt(this.pos += startSkip)
+  while (this.pos < this.input.length && !isNewLine(ch)) {
+    ch = this.input.charCodeAt(++this.pos)
+  }
+  if (this.options.onComment)
+    this.options.onComment(false, this.input.slice(start + startSkip, this.pos), start, this.pos,
+                           startLoc, this.curPosition())
+}
+
+// Called at the start of the parse and after every token. Skips
+// whitespace and comments, and.
+
+pp.skipSpace = function() {
+  loop: while (this.pos < this.input.length) {
+    let ch = this.input.charCodeAt(this.pos)
+    switch (ch) {
+    case 32: case 160: // ' '
+      ++this.pos
+      break
+    case 13:
+      if (this.input.charCodeAt(this.pos + 1) === 10) {
+        ++this.pos
+      }
+    case 10: case 8232: case 8233:
+      ++this.pos
+      if (this.options.locations) {
+        ++this.curLine
+        this.lineStart = this.pos
+      }
+      break
+    case 47: // '/'
+      switch (this.input.charCodeAt(this.pos + 1)) {
+      case 42: // '*'
+        this.skipBlockComment()
+        break
+      case 47:
+        this.skipLineComment(2)
+        break
+      default:
+        break loop
+      }
+      break
+    default:
+      if (ch > 8 && ch < 14 || ch >= 5760 && nonASCIIwhitespace.test(String.fromCharCode(ch))) {
+        ++this.pos
+      } else {
+        break loop
+      }
+    }
+  }
+}
+
+// Called at the end of every token. Sets `end`, `val`, and
+// maintains `context` and `exprAllowed`, and skips the space after
+// the token, so that the next one's `start` will point at the
+// right position.
+
+pp.finishToken = function(type, val) {
+  this.end = this.pos
+  if (this.options.locations) this.endLoc = this.curPosition()
+  let prevType = this.type
+  this.type = type
+  this.value = val
+
+  this.updateContext(prevType)
+}
+
+// ### Token reading
+
+// This is the function that is called to fetch the next token. It
+// is somewhat obscure, because it works in character codes rather
+// than characters, and because operator parsing has been inlined
+// into it.
+//
+// All in the name of speed.
+//
+pp.readToken_dot = function() {
+  let next = this.input.charCodeAt(this.pos + 1)
+  if (next >= 48 && next <= 57) return this.readNumber(true)
+  let next2 = this.input.charCodeAt(this.pos + 2)
+  if (this.options.ecmaVersion >= 6 && next === 46 && next2 === 46) { // 46 = dot '.'
+    this.pos += 3
+    return this.finishToken(tt.ellipsis)
+  } else {
+    ++this.pos
+    return this.finishToken(tt.dot)
+  }
+}
+
+pp.readToken_slash = function() { // '/'
+  let next = this.input.charCodeAt(this.pos + 1)
+  if (this.exprAllowed) { ++this.pos; return this.readRegexp() }
+  if (next === 61) return this.finishOp(tt.assign, 2)
+  return this.finishOp(tt.slash, 1)
+}
+
+pp.readToken_mult_modulo_exp = function(code) { // '%*'
+  let next = this.input.charCodeAt(this.pos + 1)
+  let size = 1
+  let tokentype = code === 42 ? tt.star : tt.modulo
+
+  // exponentiation operator ** and **=
+  if (this.options.ecmaVersion >= 7 && code == 42 && next === 42) {
+    ++size
+    tokentype = tt.starstar
+    next = this.input.charCodeAt(this.pos + 2)
+  }
+
+  if (next === 61) return this.finishOp(tt.assign, size + 1)
+  return this.finishOp(tokentype, size)
+}
+
+pp.readToken_pipe_amp = function(code) { // '|&'
+  let next = this.input.charCodeAt(this.pos + 1)
+  if (next === code) return this.finishOp(code === 124 ? tt.logicalOR : tt.logicalAND, 2)
+  if (next === 61) return this.finishOp(tt.assign, 2)
+  return this.finishOp(code === 124 ? tt.bitwiseOR : tt.bitwiseAND, 1)
+}
+
+pp.readToken_caret = function() { // '^'
+  let next = this.input.charCodeAt(this.pos + 1)
+  if (next === 61) return this.finishOp(tt.assign, 2)
+  return this.finishOp(tt.bitwiseXOR, 1)
+}
+
+pp.readToken_plus_min = function(code) { // '+-'
+  let next = this.input.charCodeAt(this.pos + 1)
+  if (next === code) {
+    if (next == 45 && !this.inModule && this.input.charCodeAt(this.pos + 2) == 62 &&
+        (this.lastTokEnd === 0 || lineBreak.test(this.input.slice(this.lastTokEnd, this.pos)))) {
+      // A `-->` line comment
+      this.skipLineComment(3)
+      this.skipSpace()
+      return this.nextToken()
+    }
+    return this.finishOp(tt.incDec, 2)
+  }
+  if (next === 61) return this.finishOp(tt.assign, 2)
+  return this.finishOp(tt.plusMin, 1)
+}
+
+pp.readToken_lt_gt = function(code) { // '<>'
+  let next = this.input.charCodeAt(this.pos + 1)
+  let size = 1
+  if (next === code) {
+    size = code === 62 && this.input.charCodeAt(this.pos + 2) === 62 ? 3 : 2
+    if (this.input.charCodeAt(this.pos + size) === 61) return this.finishOp(tt.assign, size + 1)
+    return this.finishOp(tt.bitShift, size)
+  }
+  if (next == 33 && code == 60 && !this.inModule && this.input.charCodeAt(this.pos + 2) == 45 &&
+      this.input.charCodeAt(this.pos + 3) == 45) {
+    // `<!--`, an XML-style comment that should be interpreted as a line comment
+    this.skipLineComment(4)
+    this.skipSpace()
+    return this.nextToken()
+  }
+  if (next === 61) size = 2
+  return this.finishOp(tt.relational, size)
+}
+
+pp.readToken_eq_excl = function(code) { // '=!'
+  let next = this.input.charCodeAt(this.pos + 1)
+  if (next === 61) return this.finishOp(tt.equality, this.input.charCodeAt(this.pos + 2) === 61 ? 3 : 2)
+  if (code === 61 && next === 62 && this.options.ecmaVersion >= 6) { // '=>'
+    this.pos += 2
+    return this.finishToken(tt.arrow)
+  }
+  return this.finishOp(code === 61 ? tt.eq : tt.prefix, 1)
+}
+
+pp.getTokenFromCode = function(code) {
+  switch (code) {
+  // The interpretation of a dot depends on whether it is followed
+  // by a digit or another two dots.
+  case 46: // '.'
+    return this.readToken_dot()
+
+  // Punctuation tokens.
+  case 40: ++this.pos; return this.finishToken(tt.parenL)
+  case 41: ++this.pos; return this.finishToken(tt.parenR)
+  case 59: ++this.pos; return this.finishToken(tt.semi)
+  case 44: ++this.pos; return this.finishToken(tt.comma)
+  case 91: ++this.pos; return this.finishToken(tt.bracketL)
+  case 93: ++this.pos; return this.finishToken(tt.bracketR)
+  case 123: ++this.pos; return this.finishToken(tt.braceL)
+  case 125: ++this.pos; return this.finishToken(tt.braceR)
+  case 58: ++this.pos; return this.finishToken(tt.colon)
+  case 63: ++this.pos; return this.finishToken(tt.question)
+
+  case 96: // '`'
+    if (this.options.ecmaVersion < 6) break
+    ++this.pos
+    return this.finishToken(tt.backQuote)
+
+  case 48: // '0'
+    let next = this.input.charCodeAt(this.pos + 1)
+    if (next === 120 || next === 88) return this.readRadixNumber(16) // '0x', '0X' - hex number
+    if (this.options.ecmaVersion >= 6) {
+      if (next === 111 || next === 79) return this.readRadixNumber(8) // '0o', '0O' - octal number
+      if (next === 98 || next === 66) return this.readRadixNumber(2) // '0b', '0B' - binary number
+    }
+
+  // Anything else beginning with a digit is an integer, octal
+  // number, or float.
+  case 49: case 50: case 51: case 52: case 53: case 54: case 55: case 56: case 57: // 1-9
+    return this.readNumber(false)
+
+  // Quotes produce strings.
+  case 34: case 39: // '"', "'"
+    return this.readString(code)
+
+  // Operators are parsed inline in tiny state machines. '=' (61) is
+  // often referred to. `finishOp` simply skips the amount of
+  // characters it is given as second argument, and returns a token
+  // of the type given by its first argument.
+
+  case 47: // '/'
+    return this.readToken_slash()
+
+  case 37: case 42: // '%*'
+    return this.readToken_mult_modulo_exp(code)
+
+  case 124: case 38: // '|&'
+    return this.readToken_pipe_amp(code)
+
+  case 94: // '^'
+    return this.readToken_caret()
+
+  case 43: case 45: // '+-'
+    return this.readToken_plus_min(code)
+
+  case 60: case 62: // '<>'
+    return this.readToken_lt_gt(code)
+
+  case 61: case 33: // '=!'
+    return this.readToken_eq_excl(code)
+
+  case 126: // '~'
+    return this.finishOp(tt.prefix, 1)
+  }
+
+  this.raise(this.pos, "Unexpected character '" + codePointToString(code) + "'")
+}
+
+pp.finishOp = function(type, size) {
+  let str = this.input.slice(this.pos, this.pos + size)
+  this.pos += size
+  return this.finishToken(type, str)
+}
+
+pp.readRegexp = function() {
+  let escaped, inClass, start = this.pos
+  for (;;) {
+    if (this.pos >= this.input.length) this.raise(start, "Unterminated regular expression")
+    let ch = this.input.charAt(this.pos)
+    if (lineBreak.test(ch)) this.raise(start, "Unterminated regular expression")
+    if (!escaped) {
+      if (ch === "[") inClass = true
+      else if (ch === "]" && inClass) inClass = false
+      else if (ch === "/" && !inClass) break
+      escaped = ch === "\\"
+    } else escaped = false
+    ++this.pos
+  }
+  let pattern = this.input.slice(start, this.pos)
+  ++this.pos
+  let flagsStart = this.pos
+  let flags = this.readWord1()
+  if (this.containsEsc) this.unexpected(flagsStart)
+
+  // Validate pattern
+  const state = this.regexpState || (this.regexpState = new RegExpValidationState(this))
+  state.reset(start, pattern, flags)
+  this.validateRegExpFlags(state)
+  this.validateRegExpPattern(state)
+
+  // Create Literal#value property value.
+  let value = null
+  try {
+    value = new RegExp(pattern, flags)
+  } catch (e) {
+    // ESTree requires null if it failed to instantiate RegExp object.
+    // https://github.com/estree/estree/blob/a27003adf4fd7bfad44de9cef372a2eacd527b1c/es5.md#regexpliteral
+  }
+
+  return this.finishToken(tt.regexp, {pattern, flags, value})
+}
+
+// Read an integer in the given radix. Return null if zero digits
+// were read, the integer value otherwise. When `len` is given, this
+// will return `null` unless the integer has exactly `len` digits.
+
+pp.readInt = function(radix, len) {
+  let start = this.pos, total = 0
+  for (let i = 0, e = len == null ? Infinity : len; i < e; ++i) {
+    let code = this.input.charCodeAt(this.pos), val
+    if (code >= 97) val = code - 97 + 10 // a
+    else if (code >= 65) val = code - 65 + 10 // A
+    else if (code >= 48 && code <= 57) val = code - 48 // 0-9
+    else val = Infinity
+    if (val >= radix) break
+    ++this.pos
+    total = total * radix + val
+  }
+  if (this.pos === start || len != null && this.pos - start !== len) return null
+
+  return total
+}
+
+pp.readRadixNumber = function(radix) {
+  this.pos += 2 // 0x
+  let val = this.readInt(radix)
+  if (val == null) this.raise(this.start + 2, "Expected number in radix " + radix)
+  if (isIdentifierStart(this.fullCharCodeAtPos())) this.raise(this.pos, "Identifier directly after number")
+  return this.finishToken(tt.num, val)
+}
+
+// Read an integer, octal integer, or floating-point number.
+
+pp.readNumber = function(startsWithDot) {
+  let start = this.pos
+  if (!startsWithDot && this.readInt(10) === null) this.raise(start, "Invalid number")
+  let octal = this.pos - start >= 2 && this.input.charCodeAt(start) === 48
+  if (octal && this.strict) this.raise(start, "Invalid number")
+  if (octal && /[89]/.test(this.input.slice(start, this.pos))) octal = false
+  let next = this.input.charCodeAt(this.pos)
+  if (next === 46 && !octal) { // '.'
+    ++this.pos
+    this.readInt(10)
+    next = this.input.charCodeAt(this.pos)
+  }
+  if ((next === 69 || next === 101) && !octal) { // 'eE'
+    next = this.input.charCodeAt(++this.pos)
+    if (next === 43 || next === 45) ++this.pos // '+-'
+    if (this.readInt(10) === null) this.raise(start, "Invalid number")
+  }
+  if (isIdentifierStart(this.fullCharCodeAtPos())) this.raise(this.pos, "Identifier directly after number")
+
+  let str = this.input.slice(start, this.pos)
+  let val = octal ? parseInt(str, 8) : parseFloat(str)
+  return this.finishToken(tt.num, val)
+}
+
+// Read a string value, interpreting backslash-escapes.
+
+pp.readCodePoint = function() {
+  let ch = this.input.charCodeAt(this.pos), code
+
+  if (ch === 123) { // '{'
+    if (this.options.ecmaVersion < 6) this.unexpected()
+    let codePos = ++this.pos
+    code = this.readHexChar(this.input.indexOf("}", this.pos) - this.pos)
+    ++this.pos
+    if (code > 0x10FFFF) this.invalidStringToken(codePos, "Code point out of bounds")
+  } else {
+    code = this.readHexChar(4)
+  }
+  return code
+}
+
+function codePointToString(code) {
+  // UTF-16 Decoding
+  if (code <= 0xFFFF) return String.fromCharCode(code)
+  code -= 0x10000
+  return String.fromCharCode((code >> 10) + 0xD800, (code & 1023) + 0xDC00)
+}
+
+pp.readString = function(quote) {
+  let out = "", chunkStart = ++this.pos
+  for (;;) {
+    if (this.pos >= this.input.length) this.raise(this.start, "Unterminated string constant")
+    let ch = this.input.charCodeAt(this.pos)
+    if (ch === quote) break
+    if (ch === 92) { // '\'
+      out += this.input.slice(chunkStart, this.pos)
+      out += this.readEscapedChar(false)
+      chunkStart = this.pos
+    } else {
+      if (isNewLine(ch)) this.raise(this.start, "Unterminated string constant")
+      ++this.pos
+    }
+  }
+  out += this.input.slice(chunkStart, this.pos++)
+  return this.finishToken(tt.string, out)
+}
+
+// Reads template string tokens.
+
+const INVALID_TEMPLATE_ESCAPE_ERROR = {}
+
+pp.tryReadTemplateToken = function() {
+  this.inTemplateElement = true
+  try {
+    this.readTmplToken()
+  } catch (err) {
+    if (err === INVALID_TEMPLATE_ESCAPE_ERROR) {
+      this.readInvalidTemplateToken()
+    } else {
+      throw err
+    }
+  }
+
+  this.inTemplateElement = false
+}
+
+pp.invalidStringToken = function(position, message) {
+  if (this.inTemplateElement && this.options.ecmaVersion >= 9) {
+    throw INVALID_TEMPLATE_ESCAPE_ERROR
+  } else {
+    this.raise(position, message)
+  }
+}
+
+pp.readTmplToken = function() {
+  let out = "", chunkStart = this.pos
+  for (;;) {
+    if (this.pos >= this.input.length) this.raise(this.start, "Unterminated template")
+    let ch = this.input.charCodeAt(this.pos)
+    if (ch === 96 || ch === 36 && this.input.charCodeAt(this.pos + 1) === 123) { // '`', '${'
+      if (this.pos === this.start && (this.type === tt.template || this.type === tt.invalidTemplate)) {
+        if (ch === 36) {
+          this.pos += 2
+          return this.finishToken(tt.dollarBraceL)
+        } else {
+          ++this.pos
+          return this.finishToken(tt.backQuote)
+        }
+      }
+      out += this.input.slice(chunkStart, this.pos)
+      return this.finishToken(tt.template, out)
+    }
+    if (ch === 92) { // '\'
+      out += this.input.slice(chunkStart, this.pos)
+      out += this.readEscapedChar(true)
+      chunkStart = this.pos
+    } else if (isNewLine(ch)) {
+      out += this.input.slice(chunkStart, this.pos)
+      ++this.pos
+      switch (ch) {
+      case 13:
+        if (this.input.charCodeAt(this.pos) === 10) ++this.pos
+      case 10:
+        out += "\n"
+        break
+      default:
+        out += String.fromCharCode(ch)
+        break
+      }
+      if (this.options.locations) {
+        ++this.curLine
+        this.lineStart = this.pos
+      }
+      chunkStart = this.pos
+    } else {
+      ++this.pos
+    }
+  }
+}
+
+// Reads a template token to search for the end, without validating any escape sequences
+pp.readInvalidTemplateToken = function() {
+  for (; this.pos < this.input.length; this.pos++) {
+    switch (this.input[this.pos]) {
+    case "\\":
+      ++this.pos
+      break
+
+    case "$":
+      if (this.input[this.pos + 1] !== "{") {
+        break
+      }
+    // falls through
+
+    case "`":
+      return this.finishToken(tt.invalidTemplate, this.input.slice(this.start, this.pos))
+
+    // no default
+    }
+  }
+  this.raise(this.start, "Unterminated template")
+}
+
+// Used to read escaped characters
+
+pp.readEscapedChar = function(inTemplate) {
+  let ch = this.input.charCodeAt(++this.pos)
+  ++this.pos
+  switch (ch) {
+  case 110: return "\n" // 'n' -> '\n'
+  case 114: return "\r" // 'r' -> '\r'
+  case 120: return String.fromCharCode(this.readHexChar(2)) // 'x'
+  case 117: return codePointToString(this.readCodePoint()) // 'u'
+  case 116: return "\t" // 't' -> '\t'
+  case 98: return "\b" // 'b' -> '\b'
+  case 118: return "\u000b" // 'v' -> '\u000b'
+  case 102: return "\f" // 'f' -> '\f'
+  case 13: if (this.input.charCodeAt(this.pos) === 10) ++this.pos // '\r\n'
+  case 10: // ' \n'
+    if (this.options.locations) { this.lineStart = this.pos; ++this.curLine }
+    return ""
+  default:
+    if (ch >= 48 && ch <= 55) {
+      let octalStr = this.input.substr(this.pos - 1, 3).match(/^[0-7]+/)[0]
+      let octal = parseInt(octalStr, 8)
+      if (octal > 255) {
+        octalStr = octalStr.slice(0, -1)
+        octal = parseInt(octalStr, 8)
+      }
+      this.pos += octalStr.length - 1
+      ch = this.input.charCodeAt(this.pos)
+      if ((octalStr !== "0" || ch == 56 || ch == 57) && (this.strict || inTemplate)) {
+        this.invalidStringToken(
+          this.pos - 1 - octalStr.length,
+          inTemplate
+            ? "Octal literal in template string"
+            : "Octal literal in strict mode"
+        )
+      }
+      return String.fromCharCode(octal)
+    }
+    return String.fromCharCode(ch)
+  }
+}
+
+// Used to read character escape sequences ('\x', '\u', '\U').
+
+pp.readHexChar = function(len) {
+  let codePos = this.pos
+  let n = this.readInt(16, len)
+  if (n === null) this.invalidStringToken(codePos, "Bad character escape sequence")
+  return n
+}
+
+// Read an identifier, and return it as a string. Sets `this.containsEsc`
+// to whether the word contained a '\u' escape.
+//
+// Incrementally adds only escaped chars, adding other chunks as-is
+// as a micro-optimization.
+
+pp.readWord1 = function() {
+  this.containsEsc = false
+  let word = "", first = true, chunkStart = this.pos
+  let astral = this.options.ecmaVersion >= 6
+  while (this.pos < this.input.length) {
+    let ch = this.fullCharCodeAtPos()
+    if (isIdentifierChar(ch, astral)) {
+      this.pos += ch <= 0xffff ? 1 : 2
+    } else if (ch === 92) { // "\"
+      this.containsEsc = true
+      word += this.input.slice(chunkStart, this.pos)
+      let escStart = this.pos
+      if (this.input.charCodeAt(++this.pos) != 117) // "u"
+        this.invalidStringToken(this.pos, "Expecting Unicode escape sequence \\uXXXX")
+      ++this.pos
+      let esc = this.readCodePoint()
+      if (!(first ? isIdentifierStart : isIdentifierChar)(esc, astral))
+        this.invalidStringToken(escStart, "Invalid Unicode escape")
+      word += codePointToString(esc)
+      chunkStart = this.pos
+    } else {
+      break
+    }
+    first = false
+  }
+  return word + this.input.slice(chunkStart, this.pos)
+}
+
+// Read an identifier or keyword token. Will check for reserved
+// words when necessary.
+
+pp.readWord = function() {
+  let word = this.readWord1()
+  let type = tt.name
+  if (this.keywords.test(word)) {
+    if (this.containsEsc) this.raiseRecoverable(this.start, "Escape sequence in keyword " + word)
+    type = keywordTypes[word]
+  }
+  return this.finishToken(type, word)
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/tokentype.js b/tools/tests/apps/modules/imports/links/acorn/src/tokentype.js
new file mode 100644
index 0000000000..76b145fda8
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/tokentype.js
@@ -0,0 +1,148 @@
+// ## Token types
+
+// The assignment of fine-grained, information-carrying type objects
+// allows the tokenizer to store the information it has about a
+// token in a way that is very cheap for the parser to look up.
+
+// All token type variables start with an underscore, to make them
+// easy to recognize.
+
+// The `beforeExpr` property is used to disambiguate between regular
+// expressions and divisions. It is set on all token types that can
+// be followed by an expression (thus, a slash after them would be a
+// regular expression).
+//
+// The `startsExpr` property is used to check if the token ends a
+// `yield` expression. It is set on all token types that either can
+// directly start an expression (like a quotation mark) or can
+// continue an expression (like the body of a string).
+//
+// `isLoop` marks a keyword as starting a loop, which is important
+// to know when parsing a label, in order to allow or disallow
+// continue jumps to that label.
+
+export class TokenType {
+  constructor(label, conf = {}) {
+    this.label = label
+    this.keyword = conf.keyword
+    this.beforeExpr = !!conf.beforeExpr
+    this.startsExpr = !!conf.startsExpr
+    this.isLoop = !!conf.isLoop
+    this.isAssign = !!conf.isAssign
+    this.prefix = !!conf.prefix
+    this.postfix = !!conf.postfix
+    this.binop = conf.binop || null
+    this.updateContext = null
+  }
+}
+
+function binop(name, prec) {
+  return new TokenType(name, {beforeExpr: true, binop: prec})
+}
+const beforeExpr = {beforeExpr: true}, startsExpr = {startsExpr: true}
+
+// Map keyword names to token types.
+
+export const keywords = {}
+
+// Succinct definitions of keyword token types
+function kw(name, options = {}) {
+  options.keyword = name
+  return keywords[name] = new TokenType(name, options)
+}
+
+export const types = {
+  num: new TokenType("num", startsExpr),
+  regexp: new TokenType("regexp", startsExpr),
+  string: new TokenType("string", startsExpr),
+  name: new TokenType("name", startsExpr),
+  eof: new TokenType("eof"),
+
+  // Punctuation token types.
+  bracketL: new TokenType("[", {beforeExpr: true, startsExpr: true}),
+  bracketR: new TokenType("]"),
+  braceL: new TokenType("{", {beforeExpr: true, startsExpr: true}),
+  braceR: new TokenType("}"),
+  parenL: new TokenType("(", {beforeExpr: true, startsExpr: true}),
+  parenR: new TokenType(")"),
+  comma: new TokenType(",", beforeExpr),
+  semi: new TokenType(";", beforeExpr),
+  colon: new TokenType(":", beforeExpr),
+  dot: new TokenType("."),
+  question: new TokenType("?", beforeExpr),
+  arrow: new TokenType("=>", beforeExpr),
+  template: new TokenType("template"),
+  invalidTemplate: new TokenType("invalidTemplate"),
+  ellipsis: new TokenType("...", beforeExpr),
+  backQuote: new TokenType("`", startsExpr),
+  dollarBraceL: new TokenType("${", {beforeExpr: true, startsExpr: true}),
+
+  // Operators. These carry several kinds of properties to help the
+  // parser use them properly (the presence of these properties is
+  // what categorizes them as operators).
+  //
+  // `binop`, when present, specifies that this operator is a binary
+  // operator, and will refer to its precedence.
+  //
+  // `prefix` and `postfix` mark the operator as a prefix or postfix
+  // unary operator.
+  //
+  // `isAssign` marks all of `=`, `+=`, `-=` etcetera, which act as
+  // binary operators with a very low precedence, that should result
+  // in AssignmentExpression nodes.
+
+  eq: new TokenType("=", {beforeExpr: true, isAssign: true}),
+  assign: new TokenType("_=", {beforeExpr: true, isAssign: true}),
+  incDec: new TokenType("++/--", {prefix: true, postfix: true, startsExpr: true}),
+  prefix: new TokenType("!/~", {beforeExpr: true, prefix: true, startsExpr: true}),
+  logicalOR: binop("||", 1),
+  logicalAND: binop("&&", 2),
+  bitwiseOR: binop("|", 3),
+  bitwiseXOR: binop("^", 4),
+  bitwiseAND: binop("&", 5),
+  equality: binop("==/!=/===/!==", 6),
+  relational: binop("</>/<=/>=", 7),
+  bitShift: binop("<</>>/>>>", 8),
+  plusMin: new TokenType("+/-", {beforeExpr: true, binop: 9, prefix: true, startsExpr: true}),
+  modulo: binop("%", 10),
+  star: binop("*", 10),
+  slash: binop("/", 10),
+  starstar: new TokenType("**", {beforeExpr: true}),
+
+  // Keyword token types.
+  _break: kw("break"),
+  _case: kw("case", beforeExpr),
+  _catch: kw("catch"),
+  _continue: kw("continue"),
+  _debugger: kw("debugger"),
+  _default: kw("default", beforeExpr),
+  _do: kw("do", {isLoop: true, beforeExpr: true}),
+  _else: kw("else", beforeExpr),
+  _finally: kw("finally"),
+  _for: kw("for", {isLoop: true}),
+  _function: kw("function", startsExpr),
+  _if: kw("if"),
+  _return: kw("return", beforeExpr),
+  _switch: kw("switch"),
+  _throw: kw("throw", beforeExpr),
+  _try: kw("try"),
+  _var: kw("var"),
+  _const: kw("const"),
+  _while: kw("while", {isLoop: true}),
+  _with: kw("with"),
+  _new: kw("new", {beforeExpr: true, startsExpr: true}),
+  _this: kw("this", startsExpr),
+  _super: kw("super", startsExpr),
+  _class: kw("class", startsExpr),
+  _extends: kw("extends", beforeExpr),
+  _export: kw("export"),
+  _import: kw("import"),
+  _null: kw("null", startsExpr),
+  _true: kw("true", startsExpr),
+  _false: kw("false", startsExpr),
+  _in: kw("in", {beforeExpr: true, binop: 7}),
+  _instanceof: kw("instanceof", {beforeExpr: true, binop: 7}),
+  _typeof: kw("typeof", {beforeExpr: true, prefix: true, startsExpr: true}),
+  _void: kw("void", {beforeExpr: true, prefix: true, startsExpr: true}),
+  _delete: kw("delete", {beforeExpr: true, prefix: true, startsExpr: true})
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/unicode-property-data.js b/tools/tests/apps/modules/imports/links/acorn/src/unicode-property-data.js
new file mode 100644
index 0000000000..d44f1a2c19
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/unicode-property-data.js
@@ -0,0 +1,463 @@
+const data = {
+  "$LONE": [
+    "ASCII",
+    "ASCII_Hex_Digit",
+    "AHex",
+    "Alphabetic",
+    "Alpha",
+    "Any",
+    "Assigned",
+    "Bidi_Control",
+    "Bidi_C",
+    "Bidi_Mirrored",
+    "Bidi_M",
+    "Case_Ignorable",
+    "CI",
+    "Cased",
+    "Changes_When_Casefolded",
+    "CWCF",
+    "Changes_When_Casemapped",
+    "CWCM",
+    "Changes_When_Lowercased",
+    "CWL",
+    "Changes_When_NFKC_Casefolded",
+    "CWKCF",
+    "Changes_When_Titlecased",
+    "CWT",
+    "Changes_When_Uppercased",
+    "CWU",
+    "Dash",
+    "Default_Ignorable_Code_Point",
+    "DI",
+    "Deprecated",
+    "Dep",
+    "Diacritic",
+    "Dia",
+    "Emoji",
+    "Emoji_Component",
+    "Emoji_Modifier",
+    "Emoji_Modifier_Base",
+    "Emoji_Presentation",
+    "Extender",
+    "Ext",
+    "Grapheme_Base",
+    "Gr_Base",
+    "Grapheme_Extend",
+    "Gr_Ext",
+    "Hex_Digit",
+    "Hex",
+    "IDS_Binary_Operator",
+    "IDSB",
+    "IDS_Trinary_Operator",
+    "IDST",
+    "ID_Continue",
+    "IDC",
+    "ID_Start",
+    "IDS",
+    "Ideographic",
+    "Ideo",
+    "Join_Control",
+    "Join_C",
+    "Logical_Order_Exception",
+    "LOE",
+    "Lowercase",
+    "Lower",
+    "Math",
+    "Noncharacter_Code_Point",
+    "NChar",
+    "Pattern_Syntax",
+    "Pat_Syn",
+    "Pattern_White_Space",
+    "Pat_WS",
+    "Quotation_Mark",
+    "QMark",
+    "Radical",
+    "Regional_Indicator",
+    "RI",
+    "Sentence_Terminal",
+    "STerm",
+    "Soft_Dotted",
+    "SD",
+    "Terminal_Punctuation",
+    "Term",
+    "Unified_Ideograph",
+    "UIdeo",
+    "Uppercase",
+    "Upper",
+    "Variation_Selector",
+    "VS",
+    "White_Space",
+    "space",
+    "XID_Continue",
+    "XIDC",
+    "XID_Start",
+    "XIDS"
+  ],
+  "General_Category": [
+    "Cased_Letter",
+    "LC",
+    "Close_Punctuation",
+    "Pe",
+    "Connector_Punctuation",
+    "Pc",
+    "Control",
+    "Cc",
+    "cntrl",
+    "Currency_Symbol",
+    "Sc",
+    "Dash_Punctuation",
+    "Pd",
+    "Decimal_Number",
+    "Nd",
+    "digit",
+    "Enclosing_Mark",
+    "Me",
+    "Final_Punctuation",
+    "Pf",
+    "Format",
+    "Cf",
+    "Initial_Punctuation",
+    "Pi",
+    "Letter",
+    "L",
+    "Letter_Number",
+    "Nl",
+    "Line_Separator",
+    "Zl",
+    "Lowercase_Letter",
+    "Ll",
+    "Mark",
+    "M",
+    "Combining_Mark",
+    "Math_Symbol",
+    "Sm",
+    "Modifier_Letter",
+    "Lm",
+    "Modifier_Symbol",
+    "Sk",
+    "Nonspacing_Mark",
+    "Mn",
+    "Number",
+    "N",
+    "Open_Punctuation",
+    "Ps",
+    "Other",
+    "C",
+    "Other_Letter",
+    "Lo",
+    "Other_Number",
+    "No",
+    "Other_Punctuation",
+    "Po",
+    "Other_Symbol",
+    "So",
+    "Paragraph_Separator",
+    "Zp",
+    "Private_Use",
+    "Co",
+    "Punctuation",
+    "P",
+    "punct",
+    "Separator",
+    "Z",
+    "Space_Separator",
+    "Zs",
+    "Spacing_Mark",
+    "Mc",
+    "Surrogate",
+    "Cs",
+    "Symbol",
+    "S",
+    "Titlecase_Letter",
+    "Lt",
+    "Unassigned",
+    "Cn",
+    "Uppercase_Letter",
+    "Lu"
+  ],
+  "Script": [
+    "Adlam",
+    "Adlm",
+    "Ahom",
+    "Anatolian_Hieroglyphs",
+    "Hluw",
+    "Arabic",
+    "Arab",
+    "Armenian",
+    "Armn",
+    "Avestan",
+    "Avst",
+    "Balinese",
+    "Bali",
+    "Bamum",
+    "Bamu",
+    "Bassa_Vah",
+    "Bass",
+    "Batak",
+    "Batk",
+    "Bengali",
+    "Beng",
+    "Bhaiksuki",
+    "Bhks",
+    "Bopomofo",
+    "Bopo",
+    "Brahmi",
+    "Brah",
+    "Braille",
+    "Brai",
+    "Buginese",
+    "Bugi",
+    "Buhid",
+    "Buhd",
+    "Canadian_Aboriginal",
+    "Cans",
+    "Carian",
+    "Cari",
+    "Caucasian_Albanian",
+    "Aghb",
+    "Chakma",
+    "Cakm",
+    "Cham",
+    "Cherokee",
+    "Cher",
+    "Common",
+    "Zyyy",
+    "Coptic",
+    "Copt",
+    "Qaac",
+    "Cuneiform",
+    "Xsux",
+    "Cypriot",
+    "Cprt",
+    "Cyrillic",
+    "Cyrl",
+    "Deseret",
+    "Dsrt",
+    "Devanagari",
+    "Deva",
+    "Duployan",
+    "Dupl",
+    "Egyptian_Hieroglyphs",
+    "Egyp",
+    "Elbasan",
+    "Elba",
+    "Ethiopic",
+    "Ethi",
+    "Georgian",
+    "Geor",
+    "Glagolitic",
+    "Glag",
+    "Gothic",
+    "Goth",
+    "Grantha",
+    "Gran",
+    "Greek",
+    "Grek",
+    "Gujarati",
+    "Gujr",
+    "Gurmukhi",
+    "Guru",
+    "Han",
+    "Hani",
+    "Hangul",
+    "Hang",
+    "Hanunoo",
+    "Hano",
+    "Hatran",
+    "Hatr",
+    "Hebrew",
+    "Hebr",
+    "Hiragana",
+    "Hira",
+    "Imperial_Aramaic",
+    "Armi",
+    "Inherited",
+    "Zinh",
+    "Qaai",
+    "Inscriptional_Pahlavi",
+    "Phli",
+    "Inscriptional_Parthian",
+    "Prti",
+    "Javanese",
+    "Java",
+    "Kaithi",
+    "Kthi",
+    "Kannada",
+    "Knda",
+    "Katakana",
+    "Kana",
+    "Kayah_Li",
+    "Kali",
+    "Kharoshthi",
+    "Khar",
+    "Khmer",
+    "Khmr",
+    "Khojki",
+    "Khoj",
+    "Khudawadi",
+    "Sind",
+    "Lao",
+    "Laoo",
+    "Latin",
+    "Latn",
+    "Lepcha",
+    "Lepc",
+    "Limbu",
+    "Limb",
+    "Linear_A",
+    "Lina",
+    "Linear_B",
+    "Linb",
+    "Lisu",
+    "Lycian",
+    "Lyci",
+    "Lydian",
+    "Lydi",
+    "Mahajani",
+    "Mahj",
+    "Malayalam",
+    "Mlym",
+    "Mandaic",
+    "Mand",
+    "Manichaean",
+    "Mani",
+    "Marchen",
+    "Marc",
+    "Masaram_Gondi",
+    "Gonm",
+    "Meetei_Mayek",
+    "Mtei",
+    "Mende_Kikakui",
+    "Mend",
+    "Meroitic_Cursive",
+    "Merc",
+    "Meroitic_Hieroglyphs",
+    "Mero",
+    "Miao",
+    "Plrd",
+    "Modi",
+    "Mongolian",
+    "Mong",
+    "Mro",
+    "Mroo",
+    "Multani",
+    "Mult",
+    "Myanmar",
+    "Mymr",
+    "Nabataean",
+    "Nbat",
+    "New_Tai_Lue",
+    "Talu",
+    "Newa",
+    "Nko",
+    "Nkoo",
+    "Nushu",
+    "Nshu",
+    "Ogham",
+    "Ogam",
+    "Ol_Chiki",
+    "Olck",
+    "Old_Hungarian",
+    "Hung",
+    "Old_Italic",
+    "Ital",
+    "Old_North_Arabian",
+    "Narb",
+    "Old_Permic",
+    "Perm",
+    "Old_Persian",
+    "Xpeo",
+    "Old_South_Arabian",
+    "Sarb",
+    "Old_Turkic",
+    "Orkh",
+    "Oriya",
+    "Orya",
+    "Osage",
+    "Osge",
+    "Osmanya",
+    "Osma",
+    "Pahawh_Hmong",
+    "Hmng",
+    "Palmyrene",
+    "Palm",
+    "Pau_Cin_Hau",
+    "Pauc",
+    "Phags_Pa",
+    "Phag",
+    "Phoenician",
+    "Phnx",
+    "Psalter_Pahlavi",
+    "Phlp",
+    "Rejang",
+    "Rjng",
+    "Runic",
+    "Runr",
+    "Samaritan",
+    "Samr",
+    "Saurashtra",
+    "Saur",
+    "Sharada",
+    "Shrd",
+    "Shavian",
+    "Shaw",
+    "Siddham",
+    "Sidd",
+    "SignWriting",
+    "Sgnw",
+    "Sinhala",
+    "Sinh",
+    "Sora_Sompeng",
+    "Sora",
+    "Soyombo",
+    "Soyo",
+    "Sundanese",
+    "Sund",
+    "Syloti_Nagri",
+    "Sylo",
+    "Syriac",
+    "Syrc",
+    "Tagalog",
+    "Tglg",
+    "Tagbanwa",
+    "Tagb",
+    "Tai_Le",
+    "Tale",
+    "Tai_Tham",
+    "Lana",
+    "Tai_Viet",
+    "Tavt",
+    "Takri",
+    "Takr",
+    "Tamil",
+    "Taml",
+    "Tangut",
+    "Tang",
+    "Telugu",
+    "Telu",
+    "Thaana",
+    "Thaa",
+    "Thai",
+    "Tibetan",
+    "Tibt",
+    "Tifinagh",
+    "Tfng",
+    "Tirhuta",
+    "Tirh",
+    "Ugaritic",
+    "Ugar",
+    "Vai",
+    "Vaii",
+    "Warang_Citi",
+    "Wara",
+    "Yi",
+    "Yiii",
+    "Zanabazar_Square",
+    "Zanb"
+  ]
+}
+Array.prototype.push.apply(data.$LONE, data.General_Category)
+data.gc = data.General_Category
+data.sc = data.Script_Extensions = data.scx = data.Script
+
+export default data
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/util.js b/tools/tests/apps/modules/imports/links/acorn/src/util.js
new file mode 100644
index 0000000000..9f548a140e
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/util.js
@@ -0,0 +1,11 @@
+const {hasOwnProperty, toString} = Object.prototype
+
+// Checks if an object has a property.
+
+export function has(obj, propName) {
+  return hasOwnProperty.call(obj, propName)
+}
+
+export const isArray = Array.isArray || ((obj) => (
+  toString.call(obj) === "[object Array]"
+))
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/walk/index.js b/tools/tests/apps/modules/imports/links/acorn/src/walk/index.js
new file mode 100644
index 0000000000..fdc776c8dc
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/walk/index.js
@@ -0,0 +1,370 @@
+// AST walker module for Mozilla Parser API compatible trees
+
+// A simple walk is one where you simply specify callbacks to be
+// called on specific nodes. The last two arguments are optional. A
+// simple use would be
+//
+//     walk.simple(myTree, {
+//         Expression: function(node) { ... }
+//     });
+//
+// to do something with all expressions. All Parser API node types
+// can be used to identify node types, as well as Expression,
+// Statement, and ScopeBody, which denote categories of nodes.
+//
+// The base argument can be used to pass a custom (recursive)
+// walker, and state can be used to give this walked an initial
+// state.
+
+export function simple(node, visitors, baseVisitor = base, state, override) {
+  (function c(node, st, override) {
+    let type = override || node.type, found = visitors[type]
+    baseVisitor[type](node, st, c)
+    if (found) found(node, st)
+  })(node, state, override)
+}
+
+// An ancestor walk keeps an array of ancestor nodes (including the
+// current node) and passes them to the callback as third parameter
+// (and also as state parameter when no other state is present).
+export function ancestor(node, visitors, baseVisitor = base, state) {
+  let ancestors = []
+  ;(function c(node, st, override) {
+    let type = override || node.type, found = visitors[type]
+    let isNew = node != ancestors[ancestors.length - 1]
+    if (isNew) ancestors.push(node)
+    baseVisitor[type](node, st, c)
+    if (found) found(node, st || ancestors, ancestors)
+    if (isNew) ancestors.pop()
+  })(node, state)
+}
+
+// A recursive walk is one where your functions override the default
+// walkers. They can modify and replace the state parameter that's
+// threaded through the walk, and can opt how and whether to walk
+// their child nodes (by calling their third argument on these
+// nodes).
+export function recursive(node, state, funcs, baseVisitor, override) {
+  let visitor = funcs ? exports.make(funcs, baseVisitor) : baseVisitor
+  ;(function c(node, st, override) {
+    visitor[override || node.type](node, st, c)
+  })(node, state, override)
+}
+
+function makeTest(test) {
+  if (typeof test == "string")
+    return type => type == test
+  else if (!test)
+    return () => true
+  else
+    return test
+}
+
+class Found {
+  constructor(node, state) { this.node = node; this.state = state }
+}
+
+// A full walk triggers the callback on each node
+export function full(node, callback, baseVisitor = base, state, override) {
+  (function c(node, st, override) {
+    let type = override || node.type
+    baseVisitor[type](node, st, c)
+    if (!override) callback(node, st, type)
+  })(node, state, override)
+}
+
+// An fullAncestor walk is like an ancestor walk, but triggers
+// the callback on each node
+export function fullAncestor(node, callback, baseVisitor = base, state) {
+  let ancestors = []
+  ;(function c(node, st, override) {
+    let type = override || node.type
+    let isNew = node != ancestors[ancestors.length - 1]
+    if (isNew) ancestors.push(node)
+    baseVisitor[type](node, st, c)
+    if (!override) callback(node, st || ancestors, ancestors, type)
+    if (isNew) ancestors.pop()
+  })(node, state)
+}
+
+// Find a node with a given start, end, and type (all are optional,
+// null can be used as wildcard). Returns a {node, state} object, or
+// undefined when it doesn't find a matching node.
+export function findNodeAt(node, start, end, test, baseVisitor = base, state) {
+  test = makeTest(test)
+  try {
+    (function c(node, st, override) {
+      let type = override || node.type
+      if ((start == null || node.start <= start) &&
+          (end == null || node.end >= end))
+        baseVisitor[type](node, st, c)
+      if ((start == null || node.start == start) &&
+          (end == null || node.end == end) &&
+          test(type, node))
+        throw new Found(node, st)
+    })(node, state)
+  } catch (e) {
+    if (e instanceof Found) return e
+    throw e
+  }
+}
+
+// Find the innermost node of a given type that contains the given
+// position. Interface similar to findNodeAt.
+export function findNodeAround(node, pos, test, baseVisitor = base, state) {
+  test = makeTest(test)
+  try {
+    (function c(node, st, override) {
+      let type = override || node.type
+      if (node.start > pos || node.end < pos) return
+      baseVisitor[type](node, st, c)
+      if (test(type, node)) throw new Found(node, st)
+    })(node, state)
+  } catch (e) {
+    if (e instanceof Found) return e
+    throw e
+  }
+}
+
+// Find the outermost matching node after a given position.
+export function findNodeAfter(node, pos, test, baseVisitor = base, state) {
+  test = makeTest(test)
+  try {
+    (function c(node, st, override) {
+      if (node.end < pos) return
+      let type = override || node.type
+      if (node.start >= pos && test(type, node)) throw new Found(node, st)
+      baseVisitor[type](node, st, c)
+    })(node, state)
+  } catch (e) {
+    if (e instanceof Found) return e
+    throw e
+  }
+}
+
+// Find the outermost matching node before a given position.
+export function findNodeBefore(node, pos, test, baseVisitor = base, state) {
+  test = makeTest(test)
+  let max
+  ;(function c(node, st, override) {
+    if (node.start > pos) return
+    let type = override || node.type
+    if (node.end <= pos && (!max || max.node.end < node.end) && test(type, node))
+      max = new Found(node, st)
+    baseVisitor[type](node, st, c)
+  })(node, state)
+  return max
+}
+
+// Fallback to an Object.create polyfill for older environments.
+const create = Object.create || function(proto) {
+  function Ctor() {}
+  Ctor.prototype = proto
+  return new Ctor
+}
+
+// Used to create a custom walker. Will fill in all missing node
+// type properties with the defaults.
+export function make(funcs, baseVisitor = base) {
+  let visitor = create(baseVisitor)
+  for (let type in funcs) visitor[type] = funcs[type]
+  return visitor
+}
+
+function skipThrough(node, st, c) { c(node, st) }
+function ignore(_node, _st, _c) {}
+
+// Node walkers.
+
+export const base = {}
+
+base.Program = base.BlockStatement = (node, st, c) => {
+  for (let stmt of node.body)
+    c(stmt, st, "Statement")
+}
+base.Statement = skipThrough
+base.EmptyStatement = ignore
+base.ExpressionStatement = base.ParenthesizedExpression =
+  (node, st, c) => c(node.expression, st, "Expression")
+base.IfStatement = (node, st, c) => {
+  c(node.test, st, "Expression")
+  c(node.consequent, st, "Statement")
+  if (node.alternate) c(node.alternate, st, "Statement")
+}
+base.LabeledStatement = (node, st, c) => c(node.body, st, "Statement")
+base.BreakStatement = base.ContinueStatement = ignore
+base.WithStatement = (node, st, c) => {
+  c(node.object, st, "Expression")
+  c(node.body, st, "Statement")
+}
+base.SwitchStatement = (node, st, c) => {
+  c(node.discriminant, st, "Expression")
+  for (let cs of node.cases) {
+    if (cs.test) c(cs.test, st, "Expression")
+    for (let cons of cs.consequent)
+      c(cons, st, "Statement")
+  }
+}
+base.SwitchCase = (node, st, c) => {
+  if (node.test) c(node.test, st, "Expression")
+  for (let cons of node.consequent)
+    c(cons, st, "Statement")
+}
+base.ReturnStatement = base.YieldExpression = base.AwaitExpression = (node, st, c) => {
+  if (node.argument) c(node.argument, st, "Expression")
+}
+base.ThrowStatement = base.SpreadElement =
+  (node, st, c) => c(node.argument, st, "Expression")
+base.TryStatement = (node, st, c) => {
+  c(node.block, st, "Statement")
+  if (node.handler) c(node.handler, st)
+  if (node.finalizer) c(node.finalizer, st, "Statement")
+}
+base.CatchClause = (node, st, c) => {
+  c(node.param, st, "Pattern")
+  c(node.body, st, "ScopeBody")
+}
+base.WhileStatement = base.DoWhileStatement = (node, st, c) => {
+  c(node.test, st, "Expression")
+  c(node.body, st, "Statement")
+}
+base.ForStatement = (node, st, c) => {
+  if (node.init) c(node.init, st, "ForInit")
+  if (node.test) c(node.test, st, "Expression")
+  if (node.update) c(node.update, st, "Expression")
+  c(node.body, st, "Statement")
+}
+base.ForInStatement = base.ForOfStatement = (node, st, c) => {
+  c(node.left, st, "ForInit")
+  c(node.right, st, "Expression")
+  c(node.body, st, "Statement")
+}
+base.ForInit = (node, st, c) => {
+  if (node.type == "VariableDeclaration") c(node, st)
+  else c(node, st, "Expression")
+}
+base.DebuggerStatement = ignore
+
+base.FunctionDeclaration = (node, st, c) => c(node, st, "Function")
+base.VariableDeclaration = (node, st, c) => {
+  for (let decl of node.declarations)
+    c(decl, st)
+}
+base.VariableDeclarator = (node, st, c) => {
+  c(node.id, st, "Pattern")
+  if (node.init) c(node.init, st, "Expression")
+}
+
+base.Function = (node, st, c) => {
+  if (node.id) c(node.id, st, "Pattern")
+  for (let param of node.params)
+    c(param, st, "Pattern")
+  c(node.body, st, node.expression ? "ScopeExpression" : "ScopeBody")
+}
+// FIXME drop these node types in next major version
+// (They are awkward, and in ES6 every block can be a scope.)
+base.ScopeBody = (node, st, c) => c(node, st, "Statement")
+base.ScopeExpression = (node, st, c) => c(node, st, "Expression")
+
+base.Pattern = (node, st, c) => {
+  if (node.type == "Identifier")
+    c(node, st, "VariablePattern")
+  else if (node.type == "MemberExpression")
+    c(node, st, "MemberPattern")
+  else
+    c(node, st)
+}
+base.VariablePattern = ignore
+base.MemberPattern = skipThrough
+base.RestElement = (node, st, c) => c(node.argument, st, "Pattern")
+base.ArrayPattern = (node, st, c) => {
+  for (let elt of node.elements) {
+    if (elt) c(elt, st, "Pattern")
+  }
+}
+base.ObjectPattern = (node, st, c) => {
+  for (let prop of node.properties) {
+    if (prop.type === "Property") {
+      if (prop.computed) c(prop.key, st, "Expression")
+      c(prop.value, st, "Pattern")
+    } else if (prop.type === "RestElement") {
+      c(prop.argument, st, "Pattern")
+    }
+  }
+}
+
+base.Expression = skipThrough
+base.ThisExpression = base.Super = base.MetaProperty = ignore
+base.ArrayExpression = (node, st, c) => {
+  for (let elt of node.elements) {
+    if (elt) c(elt, st, "Expression")
+  }
+}
+base.ObjectExpression = (node, st, c) => {
+  for (let prop of node.properties)
+    c(prop, st)
+}
+base.FunctionExpression = base.ArrowFunctionExpression = base.FunctionDeclaration
+base.SequenceExpression = base.TemplateLiteral = (node, st, c) => {
+  for (let expr of node.expressions)
+    c(expr, st, "Expression")
+}
+base.UnaryExpression = base.UpdateExpression = (node, st, c) => {
+  c(node.argument, st, "Expression")
+}
+base.BinaryExpression = base.LogicalExpression = (node, st, c) => {
+  c(node.left, st, "Expression")
+  c(node.right, st, "Expression")
+}
+base.AssignmentExpression = base.AssignmentPattern = (node, st, c) => {
+  c(node.left, st, "Pattern")
+  c(node.right, st, "Expression")
+}
+base.ConditionalExpression = (node, st, c) => {
+  c(node.test, st, "Expression")
+  c(node.consequent, st, "Expression")
+  c(node.alternate, st, "Expression")
+}
+base.NewExpression = base.CallExpression = (node, st, c) => {
+  c(node.callee, st, "Expression")
+  if (node.arguments)
+    for (let arg of node.arguments)
+      c(arg, st, "Expression")
+}
+base.MemberExpression = (node, st, c) => {
+  c(node.object, st, "Expression")
+  if (node.computed) c(node.property, st, "Expression")
+}
+base.ExportNamedDeclaration = base.ExportDefaultDeclaration = (node, st, c) => {
+  if (node.declaration)
+    c(node.declaration, st, node.type == "ExportNamedDeclaration" || node.declaration.id ? "Statement" : "Expression")
+  if (node.source) c(node.source, st, "Expression")
+}
+base.ExportAllDeclaration = (node, st, c) => {
+  c(node.source, st, "Expression")
+}
+base.ImportDeclaration = (node, st, c) => {
+  for (let spec of node.specifiers)
+    c(spec, st)
+  c(node.source, st, "Expression")
+}
+base.ImportSpecifier = base.ImportDefaultSpecifier = base.ImportNamespaceSpecifier = base.Identifier = base.Literal = ignore
+
+base.TaggedTemplateExpression = (node, st, c) => {
+  c(node.tag, st, "Expression")
+  c(node.quasi, st, "Expression")
+}
+base.ClassDeclaration = base.ClassExpression = (node, st, c) => c(node, st, "Class")
+base.Class = (node, st, c) => {
+  if (node.id) c(node.id, st, "Pattern")
+  if (node.superClass) c(node.superClass, st, "Expression")
+  c(node.body, st)
+}
+base.ClassBody = (node, st, c) => {
+  for (let elt of node.body)
+    c(elt, st)
+}
+base.MethodDefinition = base.Property = (node, st, c) => {
+  if (node.computed) c(node.key, st, "Expression")
+  c(node.value, st, "Expression")
+}
diff --git a/tools/tests/apps/modules/imports/links/acorn/src/whitespace.js b/tools/tests/apps/modules/imports/links/acorn/src/whitespace.js
new file mode 100644
index 0000000000..094c2e4a47
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/acorn/src/whitespace.js
@@ -0,0 +1,13 @@
+// Matches a whole line break (where CRLF is considered a single
+// line break). Used to count lines.
+
+export const lineBreak = /\r\n?|\n|\u2028|\u2029/
+export const lineBreakG = new RegExp(lineBreak.source, "g")
+
+export function isNewLine(code) {
+  return code === 10 || code === 13 || code === 0x2028 || code === 0x2029
+}
+
+export const nonASCIIwhitespace = /[\u1680\u180e\u2000-\u200a\u202f\u205f\u3000\ufeff]/
+
+export const skipWhiteSpace = /(?:\s|\/\/.*|\/\*[^]*?\*\/)*/g
diff --git a/tools/tests/apps/modules/imports/links/immutable-tuple b/tools/tests/apps/modules/imports/links/immutable-tuple
new file mode 120000
index 0000000000..0814a6ac4e
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/immutable-tuple
@@ -0,0 +1 @@
+../../node_modules/immutable-tuple
\ No newline at end of file
diff --git a/tools/tests/apps/modules/imports/links/lodash-es b/tools/tests/apps/modules/imports/links/lodash-es
new file mode 120000
index 0000000000..42a542a26b
--- /dev/null
+++ b/tools/tests/apps/modules/imports/links/lodash-es
@@ -0,0 +1 @@
+../../node_modules/lodash-es
\ No newline at end of file
diff --git a/tools/tests/apps/modules/package-lock.json b/tools/tests/apps/modules/package-lock.json
index 250f992df7..677a753fda 100644
--- a/tools/tests/apps/modules/package-lock.json
+++ b/tools/tests/apps/modules/package-lock.json
@@ -160,6 +160,9 @@
         "to-fast-properties": "2.0.0"
       }
     },
+    "acorn": {
+      "version": "file:imports/links/acorn"
+    },
     "ansi-styles": {
       "version": "3.2.1",
       "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-3.2.1.tgz",
@@ -503,6 +506,11 @@
       "resolved": "https://registry.npmjs.org/ieee754/-/ieee754-1.1.8.tgz",
       "integrity": "sha1-vjPUCsEO8ZJnAfbwii2G+/0a0+Q="
     },
+    "immutable-tuple": {
+      "version": "0.4.4",
+      "resolved": "https://registry.npmjs.org/immutable-tuple/-/immutable-tuple-0.4.4.tgz",
+      "integrity": "sha512-nJQ1HbFPgCLHMsO3Y9f55hV9z7RSloQF3PkkmKF70OxvgPT6Tz+EgY+4k64LusutkmOOlM9FGDwz2ow3CDvZCA=="
+    },
     "inherits": {
       "version": "2.0.3",
       "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.3.tgz",
@@ -621,6 +629,11 @@
       "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.5.tgz",
       "integrity": "sha512-svL3uiZf1RwhH+cWrfZn3A4+U58wbP0tGVTLQPbjplZxZ8ROD9VLuNgsRniTlLe7OlSqR79RUehXgpBW/s0IQw=="
     },
+    "lodash-es": {
+      "version": "4.17.7",
+      "resolved": "https://registry.npmjs.org/lodash-es/-/lodash-es-4.17.7.tgz",
+      "integrity": "sha512-jzqTi3vk4J5Dxq43cNjB0ekfCjPLHixoY2Sc0WHTo+0r928taLqe/VCt02vY5uQBvg0rdXgL3xWkK4X0MCmZcw=="
+    },
     "lodash.isplainobject": {
       "version": "4.0.6",
       "resolved": "https://registry.npmjs.org/lodash.isplainobject/-/lodash.isplainobject-4.0.6.tgz",
diff --git a/tools/tests/apps/modules/package.json b/tools/tests/apps/modules/package.json
index ad2bee638a..5b73b6b8ae 100644
--- a/tools/tests/apps/modules/package.json
+++ b/tools/tests/apps/modules/package.json
@@ -7,11 +7,14 @@
     "@babel/core": "^7.0.0-beta.40",
     "@babel/plugin-proposal-optional-chaining": "^7.0.0-beta.40",
     "@babel/runtime": "^7.0.0-beta.42",
+    "acorn": "file:imports/links/acorn",
     "aws-sdk": "^2.2.41",
     "babel-plugin-transform-do-expressions": "^6.22.0",
     "cli-color": "^0.2.3",
     "github": "^0.2.4",
     "idle-gc": "^1.0.1",
+    "immutable-tuple": "^0.4.4",
+    "lodash-es": "^4.17.7",
     "meteor-node-stubs": "^0.3.2",
     "moment": "2.11.1",
     "mssql": "^3.1.1",
diff --git a/tools/tests/apps/modules/tests.js b/tools/tests/apps/modules/tests.js
index e4fec9ec2f..da7464e677 100644
--- a/tools/tests/apps/modules/tests.js
+++ b/tools/tests/apps/modules/tests.js
@@ -460,6 +460,44 @@ describe("Meteor packages", () => {
   });
 });
 
+describe("symlinking node_modules", () => {
+  it("should allow selective compilation of npm packages", () => {
+    import each from "lodash-es/each";
+    import range from "lodash-es/range";
+    const n = 100;
+    let sum = 0;
+    each(range(1, n + 1), n => sum += n);
+    assert.strictEqual(sum, n * (n + 1) / 2);
+  });
+
+  it("should preserve equivalence for require", async () => {
+    const pkg1 = require("immutable-tuple/package.json");
+    const pkg2 = require("./imports/links/immutable-tuple/package");
+    assert.strictEqual(pkg1.author.name, "Ben Newman");
+    assert.strictEqual(pkg1.author, pkg2.author);
+  });
+
+  it("should preserve equivalence for dynamic import()", async () => {
+    const { default: tuple1 } = await import("immutable-tuple/src/tuple");
+    const { tuple: tuple2 } =
+      await import("/imports/links/immutable-tuple/src/tuple");
+    assert.strictEqual(tuple1, tuple2);
+  });
+
+  it("should support application-compiled `npm link`ed packages", () => {
+    assert.strictEqual(
+      require.resolve("acorn"),
+      "/node_modules/acorn/src/index.js"
+    );
+    const { parse } = require("acorn");
+    assert.strictEqual(typeof parse, "function");
+    assert.strictEqual(
+      parse,
+      require("./imports/links/acorn").parse
+    );
+  });
+});
+
 describe("ecmascript miscellany", () => {
   it("JSX should work in .js files on both client and server", () => {
     const React = {
diff --git a/tools/tests/old/test-bundler-assets.js b/tools/tests/old/test-bundler-assets.js
index 54534c5977..c66d4fad19 100644
--- a/tools/tests/old/test-bundler-assets.js
+++ b/tools/tests/old/test-bundler-assets.js
@@ -23,7 +23,9 @@ var makeProjectContext = function (appName) {
 
   var projectDir = files.mkdtemp("test-bundler-assets");
 
-  files.cp_r(testAppDir, projectDir);
+  files.cp_r(testAppDir, projectDir, {
+    preserveSymlinks: true,
+  });
 
   require("../../cli/default-npm-deps.js").install(projectDir);
 
diff --git a/tools/tests/old/test-bundler-npm.js b/tools/tests/old/test-bundler-npm.js
index 1caf634ad8..a14de5168d 100644
--- a/tools/tests/old/test-bundler-npm.js
+++ b/tools/tests/old/test-bundler-npm.js
@@ -19,8 +19,11 @@ var tmpDir = function () {
 
 var makeProjectContext = function (appName) {
   var projectDir = files.mkdtemp("test-bundler-assets");
-  files.cp_r(files.pathJoin(files.convertToStandardPath(__dirname), appName),
-    projectDir);
+  files.cp_r(
+    files.pathJoin(files.convertToStandardPath(__dirname), appName),
+    projectDir,
+    { preserveSymlinks: true },
+  );
   var projectContext = new projectContextModule.ProjectContext({
     projectDir: projectDir
   });
diff --git a/tools/tests/old/test-bundler-options.js b/tools/tests/old/test-bundler-options.js
index 2482ca4999..c2df92a0cd 100644
--- a/tools/tests/old/test-bundler-options.js
+++ b/tools/tests/old/test-bundler-options.js
@@ -18,8 +18,11 @@ var tmpDir = function () {
 
 var makeProjectContext = function (appName) {
   var projectDir = files.mkdtemp("test-bundler-options");
-  files.cp_r(files.pathJoin(files.convertToStandardPath(__dirname), appName),
-    projectDir);
+  files.cp_r(
+    files.pathJoin(files.convertToStandardPath(__dirname), appName),
+    projectDir,
+    { preserveSymlinks: true },
+  );
   var projectContext = new projectContextModule.ProjectContext({
     projectDir: projectDir
   });
diff --git a/tools/tool-testing/sandbox.js b/tools/tool-testing/sandbox.js
index 6937f0e064..91ca8d83cb 100644
--- a/tools/tool-testing/sandbox.js
+++ b/tools/tool-testing/sandbox.js
@@ -167,9 +167,14 @@ export default class Sandbox {
   createApp(to, template, options) {
     options = options || {};
     const absoluteTo = files.pathJoin(this.cwd, to);
-    files.cp_r(files.pathJoin(
-      files.convertToStandardPath(__dirname), '..', 'tests', 'apps', template),
-        absoluteTo, { ignore: [/^local$/] });
+    const absoluteFrom = files.pathJoin(
+      files.convertToStandardPath(__dirname),
+      '..', 'tests', 'apps', template
+    );
+    files.cp_r(absoluteFrom, absoluteTo, {
+      ignore: [/^local$/],
+      preserveSymlinks: true,
+    });
     // If the test isn't explicitly managing a mock warehouse, ensure that apps
     // run with our release by default.
     if (options.release) {
@@ -222,7 +227,9 @@ export default class Sandbox {
     const packagePath = files.pathJoin(this.cwd, packageDir);
     const templatePackagePath = files.pathJoin(
       files.convertToStandardPath(__dirname), '..', 'tests', 'packages', template);
-    files.cp_r(templatePackagePath, packagePath);
+    files.cp_r(templatePackagePath, packagePath, {
+      preserveSymlinks: true,
+    });
 
     files.readdir(packagePath).forEach((file) => {
       if (file.match(/^package.*\.js$/)) {