dartj2s: add constructor helpers for map literals with no type parameters.

sdk/lib/_internal/compiler/js_lib/collection_patch.dart

 // Copyright (c) 2013, 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.
 
 // Patch file for dart:collection classes.
 import 'dart:_foreign_helper' show JS;
 import 'dart:_js_helper' show
     fillLiteralMap, InternalMap, NoInline, NoThrows, patch, JsLinkedHashMap,
     LinkedHashMapCell, LinkedHashMapKeyIterable, LinkedHashMapKeyIterator;
 
@@ skipping 511 matching lines @@
   @NoInline()
   factory LinkedHashMap._literal(List keyValuePairs) {
     return fillLiteralMap(keyValuePairs, new JsLinkedHashMap<K, V>());
   }
 
   // Private factory constructor called by generated code for map literals.
   @NoThrows() @NoInline()
   factory LinkedHashMap._empty() {
     return new JsLinkedHashMap<K, V>();
   }
+
+  // Private factory static function called by generated code for map literals.
+  // This version is for map literals without type parameters.
+  @NoInline()
+  static _makeEmpty() => new JsLinkedHashMap();
+
+  // Private factory static function called by generated code for map literals.
+  // This version is for map literals without type parameters.
+  @NoInline()
+  static _makeLiteral(keyValuePairs) =>
+      fillLiteralMap(keyValuePairs, new JsLinkedHashMap());
 }
 
 class _LinkedIdentityHashMap<K, V> extends JsLinkedHashMap<K, V> {
   int internalComputeHashCode(var key) {
     // We force the hash codes to be unsigned 30-bit integers to avoid
     // issues with problematic keys like '__proto__'. Another option
     // would be to throw an exception if the hash code isn't a number.
     return JS('int', '# & 0x3ffffff', identityHashCode(key));
   }
 
@@ skipping 916 matching lines @@
     } else if (_cell == null) {
       _current = null;
       return false;
     } else {
       _current = _cell._element;
       _cell = _cell._next;
       return true;
     }
   }
 }