Adding 'part of html' to all files which are used by dart:html.

sdk/lib/html/src/ReadyState.dart

 // Copyright (c) 2011, 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;
+
 /**
  * Contains the set of standard values returned by HTMLDocument.getReadyState.
  */
 abstract class ReadyState {
   /**
    * Indicates the document is still loading and parsing.
    */
   static const String LOADING = "loading";
 
   /**
    * Indicates the document is finished parsing but is still loading
    * subresources.
    */
   static const String INTERACTIVE = "interactive";
 
   /**
    * Indicates the document and all subresources have been loaded.
    */
   static const String COMPLETE = "complete";
 }