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

Source/core/accessibility/AXSpinButton.h

 /*
  * Copyright (C) 2011 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 52 matching lines @@
 private:
     AXSpinButtonPart();
     bool m_isIncrementor : 1;
 
     virtual bool press() const OVERRIDE;
     virtual AccessibilityRole roleValue() const OVERRIDE { return ButtonRole; }
     virtual bool isSpinButtonPart() const OVERRIDE { return true; }
     virtual LayoutRect elementRect() const OVERRIDE;
 };
 
-inline AXSpinButton* toAXSpinButton(AXObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isNativeSpinButton());
-    return static_cast<AXSpinButton*>(object);
-}
-
-inline AXSpinButtonPart* toAXSpinButtonPart(AXObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isSpinButtonPart());
-    return static_cast<AXSpinButtonPart*>(object);
-}
+DEFINE_AX_OBJECT_TYPE_CASTS(AXSpinButton, isNativeSpinButton());
+DEFINE_AX_OBJECT_TYPE_CASTS(AXSpinButtonPart, isSpinButtonPart());
 
 } // namespace WebCore
 
 #endif // AXSpinButton_h