Stop adding so many global functions in client/dart.js.

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 62 matching lines @@
   num _id;
   _JsSendPortSync(this._id);
 
   callSync(var message) {
     var serialized = _serialize(message);
     var result = _call(_id, serialized);
     return _deserialize(result);
   }
 
   static _call(num id, var message) native @"""
-    var deserialized = _deserialize(message);
-    var result = ReceivePortSync.map[id].callback(deserialized);
-    return _serialize(result);
+    return ReceivePortSync.dispatchCall(id, message);
   """;
 
 }