Introduce DEFINE_AX_OBJECT_TYPE_CASTS to replace manual toFoo() in accessibility child class

Source/core/accessibility/AXMenuList.h

 /*
  * 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 37 matching lines @@
     explicit AXMenuList(RenderMenuList*);
 
     virtual bool isMenuList() const OVERRIDE { return true; }
     virtual AccessibilityRole roleValue() const OVERRIDE { return PopUpButtonRole; }
     virtual bool canSetFocusAttribute() const OVERRIDE;
 
     virtual void addChildren() OVERRIDE;
     virtual void childrenChanged() OVERRIDE;
 };
 
-inline AXMenuList* toAXMenuList(AXObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isMenuList());
-    return static_cast<AXMenuList*>(object);
-}
+DEFINE_AX_OBJECT_TYPE_CASTS(AXMenuList, isMenuList());
 
 } // namespace WebCore
 
 #endif // AXMenuList_h