Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXProgressIndicator.cpp

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 12 matching lines @@
 
 #include "core/html/HTMLProgressElement.h"
 #include "core/layout/LayoutProgress.h"
 #include "modules/accessibility/AXObjectCacheImpl.h"
 #include "platform/FloatConversion.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
-AXProgressIndicator::AXProgressIndicator(LayoutProgress* layoutObject, AXObjectCacheImpl* axObjectCache)
+AXProgressIndicator::AXProgressIndicator(LayoutProgress* layoutObject, AXObjectCacheImpl& axObjectCache)
     : AXLayoutObject(layoutObject, axObjectCache)
 {
 }
 
-PassRefPtr<AXProgressIndicator> AXProgressIndicator::create(LayoutProgress* layoutObject, AXObjectCacheImpl* axObjectCache)
+PassRefPtr<AXProgressIndicator> AXProgressIndicator::create(LayoutProgress* layoutObject, AXObjectCacheImpl& axObjectCache)
 {
     return adoptRef(new AXProgressIndicator(layoutObject, axObjectCache));
 }
 
 AccessibilityRole AXProgressIndicator::determineAccessibilityRole()
 {
     if ((m_ariaRole = determineAriaRoleAttribute()) != UnknownRole)
         return m_ariaRole;
     return ProgressIndicatorRole;
 }
@@ skipping 30 matching lines @@
     return 0.0f;
 }
 
 HTMLProgressElement* AXProgressIndicator::element() const
 {
     return toLayoutProgress(m_layoutObject)->progressElement();
 }
 
 
 } // namespace blink