Have DOMPatchSupport and DocumentFragment deal with Document references

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 1034 matching lines @@
     Locale& getCachedLocale(const AtomicString& locale = nullAtom);
 
     DocumentTimeline* timeline() const { return m_timeline.get(); }
 
     void addToTopLayer(Element*, const Element* before = 0);
     void removeFromTopLayer(Element*);
     const Vector<RefPtr<Element> >& topLayerElements() const { return m_topLayerElements; }
     HTMLDialogElement* activeModalDialog() const;
 
     const Document* templateDocument() const;
-    Document* ensureTemplateDocument();
+    Document& ensureTemplateDocument();
     void setTemplateDocumentHost(Document* templateDocumentHost) { m_templateDocumentHost = templateDocumentHost; }
     Document* templateDocumentHost() { return m_templateDocumentHost; }
 
     void didAssociateFormControl(Element*);
 
     void addConsoleMessageWithRequestIdentifier(MessageSource, MessageLevel, const String& message, unsigned long requestIdentifier);
 
     virtual DOMWindow* executingWindow() OVERRIDE { return domWindow(); }
     virtual void userEventWasHandled() OVERRIDE { resetLastHandledUserGestureTimestamp(); }
 
@@ skipping 368 matching lines @@
 inline bool Node::isDocumentNode() const
 {
     return this == documentInternal();
 }
 
 Node* eventTargetNodeForDocument(Document*);
 
 } // namespace WebCore
 
 #endif // Document_h