Implement revised factories in the VM.

runtime/lib/literal_factory.dart

Index: runtime/lib/literal_factory.dart
===================================================================
--- runtime/lib/literal_factory.dart	(revision 2391)
+++ runtime/lib/literal_factory.dart	(working copy)
@@ -2,12 +2,12 @@
 // 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.
 
-// Factory class constructing mutable List and Map objects from parser generated
-// list and map literals.
+// Factory classes constructing mutable List and Map objects from parser
+// generated list and map literals.
 
-class _LiteralFactory {
+class _ListLiteralFactory<E> {
   // [elements] contains elements that are already type checked.
-  factory List<E>.fromLiteral(List elements) {
+  factory List.fromLiteral(List elements) {
     var list = new GrowableObjectArray<E>();
     if (elements.length > 0) {
       list.backingArray = elements;
@@ -15,12 +15,17 @@
     }
     return list;
   }
+}
 
+// Factory class constructing mutable List and Map objects from parser generated
+// list and map literals.
+
+class _MapLiteralFactory<K, V> {
   // [elements] contains n key-value pairs.
   // The keys are at position 2*n and are already type checked by the parser
   // in checked mode.
   // The values are at position 2*n+1 and are not yet type checked.
-  factory Map<K, V>.fromLiteral(List elements) {
+  factory Map.fromLiteral(List elements) {
     var map = new LinkedHashMap<String, V>();
     var len = elements.length;
     for (int i = 1; i < len; i += 2) {
@@ -29,3 +34,4 @@
     return map;
   }
 }
+