Revert "Fix a few strong mode errors in dart:html"

tools/dom/templates/html/impl/impl_Document.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 $LIBRARYNAME;
 
 @DocsEditable()
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME extends Node
 {
 
@@ skipping 96 matching lines @@
   NodeIterator _createNodeIterator(Node root,
       [int whatToShow, NodeFilter filter])
       => JS('NodeIterator', '#.createNodeIterator(#, #, #, false)',
           this, root, whatToShow, filter);
 
   @DomName('Document.createTreeWalker')
   TreeWalker _createTreeWalker(Node root,
       [int whatToShow, NodeFilter filter])
       => JS('TreeWalker', '#.createTreeWalker(#, #, #, false)',
           this, root, whatToShow, filter);
-
-  /**
-   * Returns true if this document can display elements in fullscreen mode.
-   *
-   * ## Other resources
-   *
-   * * [Using the fullscreen
-   *   API](http://docs.webplatform.org/wiki/tutorials/using_the_full-screen_api)
-   *   from WebPlatform.org.
-   * * [Fullscreen specification](http://www.w3.org/TR/fullscreen/) from W3C.
-   */
-  @DomName('Document.webkitFullscreenEnabled')
-  @SupportedBrowser(SupportedBrowser.CHROME)
-  @SupportedBrowser(SupportedBrowser.SAFARI)
-  @Experimental()
-  bool get fullscreenEnabled => _webkitFullscreenEnabled;
-
 $endif
 }