Renaming dart:html library from 'html' to 'dart.html'

tools/dom/templates/html/impl/impl_MessageEvent.darttemplate

 // Copyright (c) 2013, 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.
 
 // WARNING: Do not edit - generated code.
 
-part of html;
+part of $LIBRARYNAME;
 
 $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
   factory $CLASSNAME(String type,
       {bool canBubble: false, bool cancelable: false, Object data,
       String origin, String lastEventId,
       Window source, List messagePorts}) {
     if (source == null) {
       source = window;
     }
     var event = document.$dom_createEvent("MessageEvent");
     event.$dom_initMessageEvent(type, canBubble, cancelable, data, origin,
         lastEventId, source, messagePorts);
     return event;
   }
 $!MEMBERS
 }