Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderButton.h

Index: Source/core/rendering/RenderButton.h
diff --git a/Source/core/rendering/RenderButton.h b/Source/core/rendering/RenderButton.h
index 395743df987be1e2ba97460baa1d76c5f82f796d..704b797f17465f3a68ab84035a106feb9b1274b4 100644
--- a/Source/core/rendering/RenderButton.h
+++ b/Source/core/rendering/RenderButton.h
@@ -68,20 +68,7 @@ private:
     RenderBlock* m_inner;
 };
 
-inline RenderButton* toRenderButton(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isRenderButton());
-    return static_cast<RenderButton*>(object);
-}
-
-inline const RenderButton* toRenderButton(const RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isRenderButton());
-    return static_cast<const RenderButton*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderButton(const RenderButton*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderButton, isRenderButton());
 
 } // namespace WebCore