Fix leaking AXNodeObjects when sub document detaches

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

 /*
  * Copyright (C) 2009 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 63 matching lines @@
         m_children.append(row);
     else
         m_children.appendVector(row->children());
 
     appendedRows.add(row);
     return true;
 }
 
 void AXARIAGrid::addChildren()
 {
+    ASSERT(!isDetached());
     ASSERT(!m_haveChildren);
 
     if (!isAXTable()) {
         AXLayoutObject::addChildren();
         return;
     }
 
     m_haveChildren = true;
     if (!m_layoutObject)
         return;
@@ skipping 31 matching lines @@
         if (!column->accessibilityIsIgnored())
             m_children.append(column);
     }
 
     AXObject* headerContainerObject = headerContainer();
     if (headerContainerObject && !headerContainerObject->accessibilityIsIgnored())
         m_children.append(headerContainerObject);
 }
 
 } // namespace blink