Implement cloneNode for Document

Source/core/dom/Document.h

Index: Source/core/dom/Document.h
diff --git a/Source/core/dom/Document.h b/Source/core/dom/Document.h
index a64d351294f47abb69d70340dbaef8a03d272bb9..c7a5d432ff2528648cc33016bb536da9e0dbff3e 100644
--- a/Source/core/dom/Document.h
+++ b/Source/core/dom/Document.h
@@ -1022,7 +1022,7 @@ public:
     void decrementActiveParserCount();
 
     void setContextFeatures(PassRefPtr<ContextFeatures>);
-    ContextFeatures* contextFeatures() { return m_contextFeatures.get(); }
+    ContextFeatures* contextFeatures() const { return m_contextFeatures.get(); }
 
     DocumentSharedObjectPool* sharedObjectPool() { return m_sharedObjectPool.get(); }
 
@@ -1073,6 +1073,8 @@ protected:
 
     virtual void dispose() OVERRIDE;
 
+    virtual PassRefPtr<Document> cloneDocumentWithoutChildren();
+
 private:
     friend class Node;
     friend class IgnoreDestructiveWriteCountIncrementer;
@@ -1092,6 +1094,7 @@ private:
     virtual NodeType nodeType() const;
     virtual bool childTypeAllowed(NodeType) const;
     virtual PassRefPtr<Node> cloneNode(bool deep = true);
+    void cloneDataFromDocument(const Document&);
 
     virtual void refScriptExecutionContext() { ref(); }
     virtual void derefScriptExecutionContext() { deref(); }