Fix leaking AXNodeObjects when sub document detaches

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

 /*
  * Copyright (C) 2008 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 119 matching lines @@
         return false;
 
     if (ignoredReasons)
         m_parent->computeAccessibilityIsIgnored(ignoredReasons);
 
     return true;
 }
 
 void AXTableColumn::addChildren()
 {
+    ASSERT(!isDetached());
     ASSERT(!m_haveChildren);
 
     m_haveChildren = true;
     if (!m_parent || !m_parent->isAXTable())
         return;
 
     AXTable* parentTable = toAXTable(m_parent);
     int numRows = parentTable->rowCount();
 
     for (int i = 0; i < numRows; i++) {
         AXTableCell* cell = parentTable->cellForColumnAndRow(m_columnIndex, i);
         if (!cell)
             continue;
 
         // make sure the last one isn't the same as this one (rowspan cells)
         if (m_children.size() > 0 && m_children.last() == cell)
             continue;
 
         m_children.append(cell);
         m_columnRect.unite(cell->elementRect());
     }
 }
 
 } // namespace blink