Fix leaking AXNodeObjects when sub document detaches

third_party/WebKit/Source/modules/accessibility/AXSVGRoot.cpp

 /*
  * Copyright (C) 2012 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
@@ skipping 41 matching lines @@
     // Only update the parent to another objcet if it wasn't already set to
     // something. Multiple elements in an HTML document can reference
     // the same remote SVG document, and in that case the parent should just
     // stay with the first one.
     if (!m_parent || !parent)
         m_parent = parent;
 }
 
 AXObject* AXSVGRoot::computeParent() const
 {
+    ASSERT(!isDetached());
     // If a parent was set because this is a remote SVG resource, use that
     // but otherwise, we should rely on the standard layout tree for the parent.
     if (m_parent)
         return m_parent;
 
     return AXLayoutObject::computeParent();
 }
 
 
 } // namespace blink