First experimental steps towards a better story for JS interop.

lib/dom/templates/html/frog/impl_Window.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.
 
 class $CLASSNAME$EXTENDS$IMPLEMENTS native "@*DOMWindow" {
 
   _DocumentImpl get document() native "return this.document;";
 
   Window get _top() native "return this.top;";
 
@@ skipping 100 matching lines @@
    };
    this.cancelAnimationFrame = function(id) { clearTimeout(id); }
 ''';
 
 
   _IDBFactoryImpl get indexedDB() => _get_indexedDB();
 
   _IDBFactoryImpl _get_indexedDB() native
       'return this.indexedDB || this.webkitIndexedDB || this.mozIndexedDB';
 
+  // TODO(kasperl): Document this.
+  lookupPort(String name) {
+    var port = JSON.parse(localStorage['dart-port:$name']);
+    return _deserialize(port);
+  }
+
 $!MEMBERS
 }