Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderIFrame.h

Index: Source/core/rendering/RenderIFrame.h
diff --git a/Source/core/rendering/RenderIFrame.h b/Source/core/rendering/RenderIFrame.h
index b005572999f114bd37527e029a72e876d429fc06..e8a6197c91db689587168f7108f9650a253a9707 100644
--- a/Source/core/rendering/RenderIFrame.h
+++ b/Source/core/rendering/RenderIFrame.h
@@ -58,21 +58,7 @@ private:
     RenderView* contentRootRenderer() const;
 };
 
-inline RenderIFrame* toRenderIFrame(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isRenderIFrame());
-    return static_cast<RenderIFrame*>(object);
-}
-
-inline const RenderIFrame* toRenderIFrame(const RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isRenderIFrame());
-    return static_cast<const RenderIFrame*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderIFrame(const RenderIFrame*);
-
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderIFrame, isRenderIFrame());
 
 } // namespace WebCore