Remove grunt-download-atom-shell as package dependency

package.json

@@ -132,8 +132,7 @@
     "language-todo": "0.2.0",
     "language-toml": "0.7.0",
     "language-xml": "0.2.0",
-    "language-yaml": "0.1.0",
-    "grunt-download-atom-shell": "0.4.0"
+    "language-yaml": "0.1.0"
   },
   "private": true,
   "scripts": {

src/package-manager.coffee

@@ -226,10 +226,6 @@ class PackageManager
         {@packageDependencies} = JSON.parse(fs.readFileSync(metadataPath)) ? {}
       @packageDependencies ?= {}
 
-    # Temporarily ignore 'grunt-download-atom-shell' here, should remove this
-    # when it became a public npm module.
-    delete @packageDependencies['grunt-download-atom-shell']
-
     @packageDependencies
 
   # Public: Get an array of all the available package paths.