Safely wrap window.top in frog dom.

client/dom/dom_frog.dart

 // Copyright (c) 2011, 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 DOM library.
 
 #library("dom");
 
 #source('generated/src/frog/AbstractWorker.dart');
@@ skipping 1050 matching lines @@
 #source('generated/src/interface/XPathNSResolver.dart');
 #source('generated/src/interface/XPathResult.dart');
 #source('generated/src/interface/XSLTProcessor.dart');
 
 #source('src/EventListener.dart');
 #source('src/KeyLocation.dart');
 #source('src/KeyName.dart');
 #source('src/ReadyState.dart');
 #source('src/TimeoutHandler.dart');
 #source('src/_Collections.dart');
+#source('src/frog_DOMImplementation.dart');
 #source('src/frog_DOMType.dart');
 #source('src/frog_DOMTypeJs.dart');
 #source('src/frog_FactoryProviders.dart');
 #source('src/_ListIterators.dart');
 #source('src/_Lists.dart');
 
 // TODO(sra): What 'window' do we get in a worker?  Perhaps this
 // should return the interface type.
 DOMWindow get window() native "return window;";
 
 // TODO(vsm): Revert to Dart method when 508 is fixed.
 HTMLDocument get document() native "return window.document;";