Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXTableHeaderContainer.h

 /*
  * 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 21 matching lines @@
 #include "modules/accessibility/AXMockObject.h"
 #include "modules/accessibility/AXTable.h"
 
 namespace blink {
 
 class AXObjectCacheImpl;
 
 class AXTableHeaderContainer final : public AXMockObject {
 
 private:
-    explicit AXTableHeaderContainer(AXObjectCacheImpl*);
+    explicit AXTableHeaderContainer(AXObjectCacheImpl&);
 
 public:
-    static PassRefPtr<AXTableHeaderContainer> create(AXObjectCacheImpl*);
+    static PassRefPtr<AXTableHeaderContainer> create(AXObjectCacheImpl&);
     virtual ~AXTableHeaderContainer();
 
     virtual AccessibilityRole roleValue() const override { return TableHeaderContainerRole; }
 
     virtual void addChildren() override;
 
     virtual LayoutRect elementRect() const override;
 
 private:
     LayoutRect m_headerRect;
 
     virtual bool computeAccessibilityIsIgnored(IgnoredReasons* = nullptr) const override;
 };
 
 } // namespace blink
 
 #endif // AXTableHeaderContainer_h