Fix use-after-free related to RenderFullScreen

Source/core/rendering/RenderFullScreen.cpp

 /*
  * Copyright (C) 2010 Apple 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:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 151 matching lines @@
             if (child->isBox())
                 toRenderBox(child)->clearOverrideSize();
             child->remove();
             parent()->addChild(child, this);
             parent()->setNeedsLayoutAndPrefWidthsRecalcAndFullPaintInvalidation();
         }
     }
     if (placeholder())
         placeholder()->remove();
     remove();
-    FullscreenElementStack::from(document()).setFullScreenRenderer(0);
+    destroy();
 }
 
 void RenderFullScreen::setPlaceholder(RenderBlock* placeholder)
 {
     m_placeholder = placeholder;
 }
 
 void RenderFullScreen::createPlaceholder(PassRefPtr<RenderStyle> style, const LayoutRect& frameRect)
 {
     if (style->width().isAuto())
         style->setWidth(Length(frameRect.width(), Fixed));
     if (style->height().isAuto())
         style->setHeight(Length(frameRect.height(), Fixed));
 
     if (!m_placeholder) {
         m_placeholder = new RenderFullScreenPlaceholder(this);
         m_placeholder->setStyle(style);
         if (parent()) {
             parent()->addChild(m_placeholder, this);
             parent()->setNeedsLayoutAndPrefWidthsRecalcAndFullPaintInvalidation();
         }
     } else
         m_placeholder->setStyle(style);
 }