Fix leaking AXNodeObjects when sub document detaches

third_party/WebKit/Source/modules/accessibility/AXLayoutObject.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 1208 matching lines @@
     // case SeparatorRole:
         return true;
     default:
         return false;
     }
 }
 
 AXObject* AXLayoutObject::ancestorForWhichThisIsAPresentationalChild() const
 {
     // Walk the parent chain looking for a parent that has presentational children
-    AXObject* parent = parentObject();
+    AXObject* parent = parentObjectIfExists();
     while (parent) {
         if (parent->ariaRoleHasPresentationalChildren())
             break;
 
         // The descendants of a AXMenuList that are AXLayoutObjects are all
         // presentational. (The real descendants are a AXMenuListPopup and
         // AXMenuListOptions, which are not AXLayoutObjects.)
         if (parent->isMenuList())
             break;
 
@@ skipping 317 matching lines @@
 
     return AXObject::elementAccessibilityHitTest(point);
 }
 
 //
 // High-level accessibility tree access.
 //
 
 AXObject* AXLayoutObject::computeParent() const
 {
+    ASSERT(!isDetached());
     if (!m_layoutObject)
         return 0;
 
     if (ariaRoleAttribute() == MenuBarRole)
         return axObjectCache().getOrCreate(m_layoutObject->parent());
 
     // menuButton and its corresponding menu are DOM siblings, but Accessibility needs them to be parent/child
     if (ariaRoleAttribute() == MenuRole) {
         AXObject* parent = menuButtonForMenu();
         if (parent)
@@ skipping 93 matching lines @@
     }
 
     if (!nextSibling)
         return 0;
 
     return axObjectCache().getOrCreate(nextSibling);
 }
 
 void AXLayoutObject::addChildren()
 {
+    ASSERT(!isDetached());
     // If the need to add more children in addition to existing children arises,
     // childrenChanged should have been called, leaving the object with no children.
     ASSERT(!m_haveChildren);
 
     m_haveChildren = true;
 
     if (!canHaveChildren())
         return;
 
     HeapVector<Member<AXObject>> ownedChildren;
@@ skipping 900 matching lines @@
         if (label && label->layoutObject()) {
             LayoutRect labelRect = axObjectCache().getOrCreate(label)->elementRect();
             result.unite(labelRect);
         }
     }
 
     return result;
 }
 
 } // namespace blink