Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXMenuListOption.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 15 matching lines @@
 #include "config.h"
 #include "modules/accessibility/AXMenuListOption.h"
 
 #include "modules/accessibility/AXMenuListPopup.h"
 #include "modules/accessibility/AXObjectCacheImpl.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
-AXMenuListOption::AXMenuListOption(HTMLOptionElement* element, AXObjectCacheImpl* axObjectCache)
+AXMenuListOption::AXMenuListOption(HTMLOptionElement* element, AXObjectCacheImpl& axObjectCache)
     : AXMockObject(axObjectCache)
     , m_element(element)
 {
 }
 
 void AXMenuListOption::detach()
 {
     m_element = nullptr;
     AXMockObject::detach();
 }
@@ skipping 62 matching lines @@
 
     return grandparent->elementRect();
 }
 
 String AXMenuListOption::stringValue() const
 {
     return m_element->text();
 }
 
 } // namespace blink