Enable new dart:html wrapperless frog bindings and wrapper dartium bindings.

client/html/html_frog.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.
 
 // DO NOT EDIT
 // Auto-generated dart:html library.
 
 #library("html");
 
 #source('generated/html/frog/AbstractWorker.dart');
@@ skipping 1073 matching lines @@
 _WindowImpl get _window() native "return window;";
 
 Document get document() {
   if (_cachedDocument == null) {
     _init();
   }
   return _cachedDocument;
 }
 
 _DocumentImpl get _document() native "return window.document.documentElement;";
+
+// Workaround for classes like <site> that lack their own Element subclass.
+class _HTMLElementImpl extends _ElementImpl native "*HTMLElement" {
+}