Make it possible for the embedder to run unload handlers in subframes.

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 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 2449 matching lines @@
     if (!frame)
         return true;
 
     return frame->loader().shouldClose();
 }
 
 void WebViewImpl::dispatchUnloadEvent()
 {
     // Run unload handlers.
     m_page->mainFrame()->loader().closeURL();
+    m_page->mainFrame()->loader().detachChildren();
 }
 
 WebFrame* WebViewImpl::mainFrame()
 {
     return mainFrameImpl();
 }
 
 WebFrame* WebViewImpl::findFrameByName(
     const WebString& name, WebFrame* relativeToFrame)
 {
@@ skipping 1510 matching lines @@
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return false;
 
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace blink