Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXNodeObject.h

 /*
  * Copyright (C) 2012, Google 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 25 matching lines @@
 namespace blink {
 
 class AXObjectCacheImpl;
 class Element;
 class HTMLLabelElement;
 class LayoutRect;
 class Node;
 
 class MODULES_EXPORT AXNodeObject : public AXObject {
 protected:
-    AXNodeObject(Node*, AXObjectCacheImpl*);
+    AXNodeObject(Node*, AXObjectCacheImpl&);
 
 public:
-    static PassRefPtr<AXNodeObject> create(Node*, AXObjectCacheImpl*);
+    static PassRefPtr<AXNodeObject> create(Node*, AXObjectCacheImpl&);
     virtual ~AXNodeObject();
 
 protected:
     // Protected data.
     AccessibilityRole m_ariaRole;
     bool m_childrenDirty;
 #if ENABLE(ASSERT)
     bool m_initialized;
 #endif
 
@@ skipping 160 matching lines @@
     float stepValueForRange() const;
     AXObject* findChildWithTagName(const HTMLQualifiedName&) const;
     bool isDescendantOfElementType(const HTMLQualifiedName& tagName) const;
 };
 
 DEFINE_AX_OBJECT_TYPE_CASTS(AXNodeObject, isAXNodeObject());
 
 } // namespace blink
 
 #endif // AXNodeObject_h