Changed how Experimental annotation works. No longer is a constructor.

tools/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.
 
 part of html;
 
 $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS native "@*DOMWindow" {
 
   Document get document => JS('Document', '#.document', this);
 
@@ skipping 113 matching lines @@
 
   /**
    * Gets an instance of the Indexed DB factory to being using Indexed DB.
    *
    * Use [IdbFactory.supported] to check if Indexed DB is supported on the
    * current platform.
    */
   @SupportedBrowser(SupportedBrowser.CHROME, '23.0')
   @SupportedBrowser(SupportedBrowser.FIREFOX, '15.0')
   @SupportedBrowser(SupportedBrowser.IE, '10.0')
-  @Experimental()
+  @Experimental
   IdbFactory get indexedDB =>
       JS('IdbFactory',
          '#.indexedDB || #.webkitIndexedDB || #.mozIndexedDB',
          this, this, this);
 
   /**
    * Lookup a port by its [name].  Return null if no port is
    * registered under [name].
    */
   SendPortSync lookupPort(String name) {
     var port = json.parse(document.documentElement.attributes['dart-port:$name']);
     return _deserialize(port);
   }
 
   /**
    * Register a [port] on this window under the given [name].  This
    * port may be retrieved by any isolate (or JavaScript script)
    * running in this window.
    */
   void registerPort(String name, var port) {
     var serialized = _serialize(port);
     document.documentElement.attributes['dart-port:$name'] = json.stringify(serialized);
   }
 
   @DomName('Window.console')
   Console get console => Console.safeConsole;
 
 $!MEMBERS
 }