Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderFrameSet.h

Index: Source/core/rendering/RenderFrameSet.h
diff --git a/Source/core/rendering/RenderFrameSet.h b/Source/core/rendering/RenderFrameSet.h
index b4a9a5179b2db65b611aad3f53af0051726a4b19..21f90eac87ad9f34869908466045e6e1ff5d48dd 100644
--- a/Source/core/rendering/RenderFrameSet.h
+++ b/Source/core/rendering/RenderFrameSet.h
@@ -132,15 +132,7 @@ private:
     bool m_isChildResizing;
 };
 
-
-inline RenderFrameSet* toRenderFrameSet(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isFrameSet());
-    return static_cast<RenderFrameSet*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderFrameSet(const RenderFrameSet*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderFrameSet, isFrameSet());
 
 } // namespace WebCore