Don't create layout objects for children of display-none iframes.

third_party/WebKit/Source/core/dom/Node.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004-2011, 2014 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 548 matching lines @@
   // Integration with layout tree
 
   // As layoutObject() includes a branch you should avoid calling it repeatedly
   // in hot code paths.
   // Note that if a Node has a layoutObject, it's parentNode is guaranteed to
   // have one as well.
   LayoutObject* layoutObject() const {
     return hasRareData() ? m_data.m_rareData->layoutObject()
                          : m_data.m_layoutObject;
   }
-  void setLayoutObject(LayoutObject* layoutObject) {
+  virtual void setLayoutObject(LayoutObject* layoutObject) {
     if (hasRareData())
       m_data.m_rareData->setLayoutObject(layoutObject);
     else
       m_data.m_layoutObject = layoutObject;
   }
 
   // Use these two methods with caution.
   LayoutBox* layoutBox() const;
   LayoutBoxModelObject* layoutBoxModelObject() const;
 
@@ skipping 437 matching lines @@
 }  // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showNode(const blink::Node*);
 void showTree(const blink::Node*);
 void showNodePath(const blink::Node*);
 #endif
 
 #endif  // Node_h