Revert "Implementing window.createObjectURL*"

lib/dom/templates/html/dart2js/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 111 matching lines @@
   lookupPort(String name) {
     var port = JSON.parse(localStorage['dart-port:$name']);
     return _deserialize(port);
   }
 
   registerPort(String name, var port) {
     var serialized = _serialize(port);
     localStorage['dart-port:$name'] = JSON.stringify(serialized);
   }
 
-  String createObjectUrl(object) native '''
-    return (window.URL || window.webkitURL).createObjectURL(object)
-  ''';
-
-  void revokeObjectUrl(String objectUrl) native '''
-    (window.URL || window.webkitURL).revokeObjectURL(objectUrl)
-  ''';
 $!MEMBERS
 }