Add support for DocumentFragment.getElementById()

Source/core/dom/Document.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 234 matching lines @@
 
     MediaQueryMatcher& mediaQueryMatcher();
 
     void mediaQueryAffectingValueChanged();
 
     using ContainerNode::ref;
     using ContainerNode::deref;
     using SecurityContext::securityOrigin;
     using SecurityContext::contentSecurityPolicy;
     using ExecutionContextClient::addConsoleMessage;
+    using TreeScope::getElementById;
 
     virtual bool canContainRangeEndPoint() const OVERRIDE { return true; }
 
     SelectorQueryCache& selectorQueryCache();
 
     // Focus Management.
     Element* activeElement() const;
     bool hasFocus() const;
 
     // DOM methods & attributes for Document
@@ skipping 1168 matching lines @@
 inline bool Node::isDocumentNode() const
 {
     return this == document();
 }
 
 Node* eventTargetNodeForDocument(Document*);
 
 } // namespace WebCore
 
 #endif // Document_h