Split the frame tree logic out of HistoryItem

Source/web/WebFrameImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 493 matching lines @@
     bool m_findMatchRectsAreValid;
 
     // Contents size when find-in-page match rects were last computed for this
     // frame's cache.
     WebCore::IntSize m_contentsSizeForCurrentFindMatchRects;
 
     // Valid between calls to BeginPrint() and EndPrint(). Containts the print
     // information. Is used by PrintPage().
     OwnPtr<ChromePrintContext> m_printContext;
 
-    // Ensure we don't overwrite valid history data during same document loads
-    // from HistoryItems
-    bool m_inSameDocumentHistoryLoad;
-
     // Stores the additional input events offset and scale when device metrics emulation is enabled.
     WebCore::IntSize m_inputEventsOffsetForEmulation;
     float m_inputEventsScaleFactorForEmulation;
 };
 
 inline WebFrameImpl* toWebFrameImpl(WebFrame* webFrame)
 {
     return static_cast<WebFrameImpl*>(webFrame);
 }
 
 inline const WebFrameImpl* toWebFrameImpl(const WebFrame* webFrame)
 {
     return static_cast<const WebFrameImpl*>(webFrame);
 }
 
 // This will catch anyone doing an unnecessary cast.
 void toWebFrameImpl(const WebFrameImpl*);
 
 } // namespace blink
 
 #endif