Use factory constructor for list literals

tool/input_sdk/private/js_array.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart._interceptors;
 
 /**
  * The interceptor class for [List]. The compiler recognizes this
  * class as an interceptor, and changes references to [:this:] to
  * actually use the receiver of the method, which is generated as an extra
  * argument added to each member.
  */
 @JsPeerInterface(name: 'Array')
 class JSArray<E> implements List<E>, JSIndexable {
 
   const JSArray();
 
   /**
    * Constructor for adding type parameters to an existing JavaScript Array.
    */
   factory JSArray.typed(allocation) =>
       // TODO(jmesserly): skip this when E is dynamic and Object.
       JS('-dynamic', 'dart.list(#, #)', allocation, E);
 
+  /**
+   * Constructor for adding type parameters to an existing JavaScript
+   * Array. Used for creating literal lists.
+   */
+  factory JSArray.of(allocation) {
+    // TODO(sra): Move this to core.List for better readability.
+    // Capture the parameterized ES6 'JSArray' class.
+    return JS('-dynamic', 'dart.setType(#, JSArray)', allocation);
+  }
+
   // TODO(jmesserly): consider a fixed array subclass instead.
   factory JSArray.markFixed(allocation) =>
       new JSArray<E>.typed(markFixedList(allocation));
 
   factory JSArray.markGrowable(allocation) = JSArray<E>.typed;
 
   static List markFixedList(List list) {
     // Functions are stored in the hidden class and not as properties in
     // the object. We never actually look at the value, but only want
     // to know if the property exists.
@@ skipping 569 matching lines @@
 
     if (_index >= length) {
       _current = null;
       return false;
     }
     _current = _iterable[_index];
     _index++;
     return true;
   }
 }