Fix performance of array literals (e.g. "[1, 2]"). Improves speed of DeltaBlue.

runtime/lib/array_patch.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.
 
 // Note that the optimizing compiler depends on the algorithm which
 // returns a _GrowableObjectArray if length is null, otherwise returns
 // fixed size array.
 patch class List<E> {
   /* patch */ factory List([int length = 0]) {
     if ((length is! int) || (length < 0)) {
@@ skipping 27 matching lines @@
       for (int i = 0; i < length; i++) {
         result[i] = fill;
       }
     }
     return result;
   }
 
   // Factory constructing a mutable List from a parser generated List literal.
   // [elements] contains elements that are already type checked.
   factory List._fromLiteral(List elements) {
-    var list = new List<E>();
-    if (elements.length > 0) {
-      list._setData(elements);
-      list.length = elements.length;
+    if (elements.isEmpty) {
+      return new _GrowableObjectArray<E>(0);
     }
-    return list;
+    var result = new _GrowableObjectArray<E>.withData(elements);
+    result._setLength(elements.length);
+    return result;
   }
 
   static void _throwArgumentError(int length) {
     throw new ArgumentError("Length must be a positive integer: $length.");
   }
 }