Plumb an event through to content/ that is sent just before 'onload'.

Source/WebCore/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ skipping 2345 matching lines @@
     return count;
 }
 
 String FrameLoader::userAgent(const KURL& url) const
 {
     String userAgent = m_client->userAgent(url);
     InspectorInstrumentation::applyUserAgentOverride(m_frame, &userAgent);
     return userAgent;
 }
 
+void FrameLoader::willHandleOnloadEvents()
+{
+    m_client->dispatchWillHandleOnloadEvents();
+}
+
 void FrameLoader::handledOnloadEvents()
 {
     m_client->dispatchDidHandleOnloadEvents();
 
     if (documentLoader())
         documentLoader()->handledOnloadEvents();
 }
 
 void FrameLoader::frameDetached()
 {
@@ skipping 1039 matching lines @@
     FloatRect newWindowRect = DOMWindow::adjustWindowRect(page, windowRect);
 
     page->chrome()->setWindowRect(newWindowRect);
     page->chrome()->show();
 
     created = true;
     return frame;
 }
 
 } // namespace WebCore