Implement spawnDomFunction

lib/dom/templates/html/dart2js/html_dart2js.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('dart:html');
 
 #import('dart:isolate');
@@ skipping 45 matching lines @@
   if (!window.$dart$isolate$counter) {
     window.$dart$isolate$counter = 1;
   }
   return window.$dart$isolate$counter++;
 ''';
 
 // Fast path to invoke JS send port.
 _callPortSync(int id, message) {
   return JS('var', @'ReceivePortSync.dispatchCall(#, #)', id, message);
 }
+
+// TODO(vsm): Plumb this properly.
+spawnDomFunction(f) => spawnFunction(f);