Add the JS helper function to all libraries where we allow the native syntax.

lib/dom/templates/html/frog/html_frog.darttemplate

 // 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.
 
 // DO NOT EDIT
 // Auto-generated dart:html library.
 
 #library('html');
 
 #import('dart:isolate');
@@ skipping 57 matching lines @@
 
 }
 
 class _JsSendPortSync implements SendPortSync {
 
   num _id;
   _JsSendPortSync(this._id);
 
   callSync(var message) {
     var serialized = _serialize(message);
-    var result = _call(_id, serialized);
+    var result =
+        JS('var', @'ReceivePortSync.dispatchCall(#, #)', _id, serialized);
     return _deserialize(result);
   }
 
-  static _call(num id, var message) native @"""
-    return ReceivePortSync.dispatchCall(id, message);
-  """;
-
 }