Refactoring: Simplify DocumentWriter by reorganizing its lifetime.

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 512 matching lines @@
     AXObjectCache* axObjectCache() const;
     void clearAXObjectCache();
 
     // to get visually ordered hebrew and arabic pages right
     void setVisuallyOrdered();
     bool visuallyOrdered() const { return m_visuallyOrdered; }
     
     DocumentLoader* loader() const;
 
     void open(Document* ownerDocument = 0);
-    void implicitOpen();
+    PassRefPtr<DocumentParser> implicitOpen();
 
     // close() is the DOM API document.close()
     void close();
     // In some situations (see the code), we ignore document.close().
     // explicitClose() bypass these checks and actually tries to close the
     // input stream.
     void explicitClose();
     // implicitClose() actually does the work of closing the input stream.
     void implicitClose();
 
@@ skipping 901 matching lines @@
 inline bool Node::isDocumentNode() const
 {
     return this == documentInternal();
 }
 
 Node* eventTargetNodeForDocument(Document*);
 
 } // namespace WebCore
 
 #endif // Document_h