Detach old frame on WebFrame::swap.

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 134 matching lines @@
     SecurityContext::InsecureNavigationsSet* insecureNavigationsToUpgrade() const;
 
     Frame* opener();
     void setOpener(LocalFrame*);
 
     void detach();
 
     void finishedParsing();
     void checkCompleted();
 
+    // This prepares the FrameLoader for the next commit. It will dispatch
+    // unload events, abort XHR requests and detach the document. Returns true
+    // if the frame is ready to receive the next commit, or false otherwise.
+    bool prepareForCommit();
+
     void commitProvisionalLoad();
 
     FrameLoaderStateMachine* stateMachine() const { return &m_stateMachine; }
 
     void applyUserAgent(ResourceRequest&);
 
     bool shouldInterruptLoadForXFrameOptions(const String&, const KURL&, unsigned long requestIdentifier);
 
     bool allAncestorsAreComplete() const; // including this
 
@@ skipping 93 matching lines @@
     Timer<FrameLoader> m_didAccessInitialDocumentTimer;
 
     SandboxFlags m_forcedSandboxFlags;
 
     bool m_dispatchingDidClearWindowObjectInMainWorld;
 };
 
 } // namespace blink
 
 #endif // FrameLoader_h