Do not trigger new history entry if iframe URL doesn't change

Source/core/loader/FrameLoader.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 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:
  *
@@ skipping 105 matching lines @@
     DocumentLoader* documentLoader() const { return m_documentLoader.get(); }
     DocumentLoader* policyDocumentLoader() const { return m_policyDocumentLoader.get(); }
     DocumentLoader* provisionalDocumentLoader() const { return m_provisionalDocumentLoader.get(); }
     FrameState state() const { return m_state; }
     FetchContext& fetchContext() const { return *m_fetchContext; }
 
     void receivedMainResourceError(const ResourceError&);
 
     bool isLoadingMainFrame() const;
 
+    bool shouldTreatURLAsSameAsCurrent(const KURL&) const;
     bool shouldTreatURLAsSrcdocDocument(const KURL&) const;
 
     FrameLoadType loadType() const;
     void setLoadType(FrameLoadType loadType) { m_loadType = loadType; }
 
     void checkLoadComplete(DocumentLoader*);
     void checkLoadComplete();
 
     static void addHTTPOriginIfNeeded(ResourceRequest&, const AtomicString& origin);
 
@@ skipping 146 matching lines @@
 
     bool m_didAccessInitialDocument;
     Timer<FrameLoader> m_didAccessInitialDocumentTimer;
 
     SandboxFlags m_forcedSandboxFlags;
 };
 
 } // namespace WebCore
 
 #endif // FrameLoader_h