Share the JavaScript based LinkedHashMap implementation between constant maps and the LinkedHashMap…

sdk/lib/_internal/compiler/js_lib/constant_map.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 _js_helper;
 
 abstract class ConstantMap<K, V> implements Map<K, V> {
   const ConstantMap._();
 
   bool get isEmpty => length == 0;
@@ skipping 96 matching lines @@
   GeneralConstantMap(this._jsData) : super._();
 
   // [_jsData] holds a key-value pair list.
   final _jsData;
 
   // We cannot create the backing map on creation since hashCode interceptors
   // have not been defined when constants are created.
   Map<K, V> _getMap() {
     LinkedHashMap<K, V> backingMap = JS('LinkedHashMap|Null', r'#.$map', this);
     if (backingMap == null) {
-      backingMap = new LinkedHashMap<K, V>();
+      backingMap = new JsLinkedHashMap<K, V>();
       fillLiteralMap(_jsData, backingMap);
       JS('', r'#.$map = #', this, backingMap);
     }
     return backingMap;
   }
 
   bool containsValue(V needle) {
     return _getMap().containsValue(needle);
   }
 
@@ skipping 12 matching lines @@
   Iterable<K> get keys {
     return _getMap().keys;
   }
 
   Iterable<V> get values {
     return _getMap().values;
   }
 
   int get length => _getMap().length;
 }