Oilpan: make DocumentFragment a heap allocated object.

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 303 matching lines @@
     {
         return m_documentElement.get();
     }
 
     // Returns whether the Document has an AppCache manifest.
     bool hasAppCacheManifest() const;
 
     Location* location() const;
 
     PassRefPtrWillBeRawPtr<Element> createElement(const AtomicString& name, ExceptionState&);
-    PassRefPtr<DocumentFragment> createDocumentFragment();
+    PassRefPtrWillBeRawPtr<DocumentFragment> createDocumentFragment();
     PassRefPtrWillBeRawPtr<Text> createTextNode(const String& data);
     PassRefPtrWillBeRawPtr<Comment> createComment(const String& data);
     PassRefPtrWillBeRawPtr<CDATASection> createCDATASection(const String& data, ExceptionState&);
     PassRefPtrWillBeRawPtr<ProcessingInstruction> createProcessingInstruction(const String& target, const String& data, ExceptionState&);
     PassRefPtr<Attr> createAttribute(const AtomicString& name, ExceptionState&);
     PassRefPtr<Attr> createAttributeNS(const AtomicString& namespaceURI, const AtomicString& qualifiedName, ExceptionState&, bool shouldIgnoreNamespaceChecks = false);
     PassRefPtr<Node> importNode(Node* importedNode, ExceptionState&);
     PassRefPtr<Node> importNode(Node* importedNode, bool deep, ExceptionState&);
     PassRefPtrWillBeRawPtr<Element> createElementNS(const AtomicString& namespaceURI, const AtomicString& qualifiedName, ExceptionState&);
     PassRefPtrWillBeRawPtr<Element> createElement(const QualifiedName&, bool createdByParser);
@@ skipping 1119 matching lines @@
 inline bool Node::isDocumentNode() const
 {
     return this == document();
 }
 
 Node* eventTargetNodeForDocument(Document*);
 
 } // namespace WebCore
 
 #endif // Document_h