Fix leaking AXNodeObjects when sub document detaches

third_party/WebKit/Source/modules/accessibility/AXMenuListPopup.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 84 matching lines @@
 {
     if (!m_parent)
         return false;
 
     m_parent->press();
     return true;
 }
 
 void AXMenuListPopup::addChildren()
 {
+    ASSERT(!isDetached());
     if (!m_parent)
         return;
 
     Node* parentNode = m_parent->node();
     if (!isHTMLSelectElement(parentNode))
         return;
 
     HTMLSelectElement* htmlSelectElement = toHTMLSelectElement(parentNode);
     m_haveChildren = true;
 
@@ skipping 63 matching lines @@
 
 AXObject* AXMenuListPopup::activeChild()
 {
     if (m_activeIndex < 0 || m_activeIndex >= static_cast<int>(children().size()))
         return nullptr;
 
     return m_children[m_activeIndex].get();
 }
 
 } // namespace blink