Prevent reentrancy of WebFrameClient::didClearWindowObject.

Source/core/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 1347 matching lines @@
     client()->documentElementAvailable();
 }
 
 void FrameLoader::dispatchDidClearDocumentOfWindowObject()
 {
     if (!m_frame->script().canExecuteScripts(NotAboutToExecuteScript))
         return;
 
     InspectorInstrumentation::didClearDocumentOfWindowObject(m_frame);
 
+    if (m_dispatchingDidClearWindowObjectInMainWorld)
+        return;
+    TemporaryChange<bool>
+        inDidClearWindowObject(m_dispatchingDidClearWindowObjectInMainWorld, true);
     // We just cleared the document, not the entire window object, but for the
     // embedder that's close enough.
     client()->dispatchDidClearWindowObjectInMainWorld();
 }
 
 void FrameLoader::dispatchDidClearWindowObjectInMainWorld()
 {
     if (!m_frame->script().canExecuteScripts(NotAboutToExecuteScript))
         return;
 
@@ skipping 55 matching lines @@
     // FIXME: We need a way to propagate insecure requests policy flags to
     // out-of-process frames. For now, we'll always use default behavior.
     if (!parentFrame->isLocalFrame())
         return nullptr;
 
     ASSERT(toLocalFrame(parentFrame)->document());
     return toLocalFrame(parentFrame)->document()->insecureNavigationsToUpgrade();
 }
 
 } // namespace blink