Don't reuse HistoryItems for multiple navigations

Source/core/loader/HistoryItem.h

 /*
  * Copyright (C) 2006, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Research In Motion Limited. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 35 matching lines @@
 class ResourceRequest;
 
 class CORE_EXPORT HistoryItem final : public RefCountedWillBeGarbageCollectedFinalized<HistoryItem> {
 public:
     static PassRefPtrWillBeRawPtr<HistoryItem> create()
     {
         return adoptRefWillBeNoop(new HistoryItem);
     }
     ~HistoryItem();
 
-    // Used when the frame this item represents was navigated to a different
-    // url but a new item wasn't created.
-    void generateNewItemSequenceNumber();
-    void generateNewDocumentSequenceNumber();
-
     const String& urlString() const;
     KURL url() const;
 
     const Referrer& referrer() const;
     const String& target() const;
 
     FormData* formData();
     const AtomicString& formContentType() const;
 
     const FloatPoint& pinchViewportScrollPoint() const;
     void setPinchViewportScrollPoint(const FloatPoint&);
     const IntPoint& scrollPoint() const;
     void setScrollPoint(const IntPoint&);
-    void clearScrollPoint();
 
     float pageScaleFactor() const;
     void setPageScaleFactor(float);
 
     Vector<String> getReferencedFilePaths();
     const Vector<String>& documentState();
     void setDocumentState(const Vector<String>&);
     void setDocumentState(DocumentState*);
     void clearDocumentState();
 
@@ skipping 55 matching lines @@
 
     // info used to repost form data
     RefPtr<FormData> m_formData;
     AtomicString m_formContentType;
 
 }; // class HistoryItem
 
 } // namespace blink
 
 #endif // HISTORYITEM_H