Don't include line number comments in isopackets

The extra legibility is not as useful for code that is always part of
core as it is for user's packages, and it actually has a notable (25%)
effect on isopacket load time.

Fixes #3218.

tools/compiler.js

@@ -45,6 +45,9 @@ compiler.compile = function (packageSource, options) {
         "` in package `" + packageSource.name + "`",
       rootPath: packageSource.sourceRoot
     }, function () {
+      // XXX we should probably also pass options.noLineNumbers into
+      //     buildJsImage so it can pass it back to its call to
+      //     compiler.compile
       var buildResult = bundler.buildJsImage({
         name: info.name,
         packageMap: packageMap,
@@ -125,7 +128,8 @@ compiler.compile = function (packageSource, options) {
       sourceArch: unibuild,
       isopackCache: isopackCache,
       nodeModulesPath: nodeModulesPath,
-      isPortable: isPortable
+      isPortable: isPortable,
+      noLineNumbers: options.noLineNumbers
     });
     _.extend(pluginProviderPackageNames,
              unibuildResult.pluginProviderPackageNames);
@@ -150,6 +154,7 @@ var compileUnibuild = function (options) {
   var isopackCache = options.isopackCache;
   var nodeModulesPath = options.nodeModulesPath;
   var isPortable = options.isPortable;
+  var noLineNumbers = options.noLineNumbers;
 
   var isApp = ! inputSourceArch.pkg.name;
   var resources = [];
@@ -738,7 +743,8 @@ var compileUnibuild = function (options) {
       (inputSourceArch.kind === "main" ? "" : (":" + inputSourceArch.kind)) + ".js",
     name: inputSourceArch.pkg.name || null,
     declaredExports: _.pluck(inputSourceArch.declaredExports, 'name'),
-    jsAnalyze: jsAnalyze
+    jsAnalyze: jsAnalyze,
+    noLineNumbers: noLineNumbers
   });
 
   // *** Determine captured variables

tools/isopack-cache.js

@@ -36,6 +36,8 @@ exports.IsopackCache = function (options) {
   // tropohouse, and otherwise is a PackageMap object listing
   self._isopacks = {};
 
+  self._noLineNumbers = !! options.noLineNumbers;
+
   self.allLoadedLocalPackagesWatchSet = new watch.WatchSet;
 };
 
@@ -204,7 +206,8 @@ _.extend(exports.IsopackCache.prototype, {
         // Nope! Compile it again.
         var compilerResult = compiler.compile(packageInfo.packageSource, {
           packageMap: self._packageMap,
-          isopackCache: self
+          isopackCache: self,
+          noLineNumbers: self._noLineNumbers
         });
         // Accept the compiler's result, even if there were errors (since it at
         // least will have a useful WatchSet and will allow us to keep going and

tools/isopackets.js

@@ -236,7 +236,13 @@ var makeIsopacketBuildContext = function () {
   // Make an isopack cache that doesn't save isopacks to disk and has no
   // access to versioned packages.
   context.isopackCache = new isopackCacheModule.IsopackCache({
-    packageMap: context.packageMap
+    packageMap: context.packageMap,
+    // When linking JS files, don't include the padding spaces and line number
+    // comments. Since isopackets are loaded as part of possibly very short
+    // 'meteor' tool command invocations, we care more about startup time than
+    // legibility, and the difference is actually observable (eg 25% speedup
+    // loading constraint-solver).
+    noLineNumbers: true
   });
   return context;
 };

tools/linker.js

@@ -32,6 +32,7 @@ var Module = function (options) {
   self.combinedServePath = options.combinedServePath;
   self.importStubServePath = options.importStubServePath;
   self.jsAnalyze = options.jsAnalyze;
+  self.noLineNumbers = options.noLineNumbers;
 };
 
 _.extend(Module.prototype, {
@@ -134,7 +135,10 @@ _.extend(Module.prototype, {
     _.each(self.files, function (file) {
       if (!_.isEmpty(chunks))
         chunks.push("\n\n\n\n\n\n");
-      chunks.push(file.getPrelinkedOutput({ sourceWidth: sourceWidth }));
+      chunks.push(file.getPrelinkedOutput({
+        sourceWidth: sourceWidth,
+        noLineNumbers: self.noLineNumbers
+      }));
     });
 
     var node = new sourcemap.SourceNode(null, null, null, chunks);
@@ -291,6 +295,8 @@ _.extend(File.prototype, {
   // - preserveLineNumbers: if true, decorate minimally so that line
   //   numbers don't change between input and output. In this case,
   //   sourceWidth is ignored.
+  // - noLineNumbers: We still include the banners and such, but
+  //   no line number suffix.
   // - sourceWidth: width in columns to use for the source code
   //
   // Returns a SourceNode.
@@ -355,7 +361,8 @@ _.extend(File.prototype, {
       _.each(lines, function (line) {
         var suffix = "\n";
 
-        if (line.length <= width && line[line.length - 1] !== "\\") {
+        if (! options.noLineNumbers
+            && line.length <= width && line[line.length - 1] !== "\\") {
           suffix = padding.slice(line.length, width) + " // " + num + "\n";
         }
         f(line, suffix, num);
@@ -494,7 +501,8 @@ var prelink = function (options) {
     useGlobalNamespace: options.useGlobalNamespace,
     importStubServePath: options.importStubServePath,
     combinedServePath: options.combinedServePath,
-    jsAnalyze: options.jsAnalyze
+    jsAnalyze: options.jsAnalyze,
+    noLineNumbers: options.noLineNumbers
   });
 
   _.each(options.inputFiles, function (inputFile) {