Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/svg/RenderSVGViewportContainer.h

Index: Source/core/rendering/svg/RenderSVGViewportContainer.h
diff --git a/Source/core/rendering/svg/RenderSVGViewportContainer.h b/Source/core/rendering/svg/RenderSVGViewportContainer.h
index c01e7a582d170f5edc8b74fbe3c7447a95a842ff..b1b79ed5e31e884af09644e980def2370f11f773 100644
--- a/Source/core/rendering/svg/RenderSVGViewportContainer.h
+++ b/Source/core/rendering/svg/RenderSVGViewportContainer.h
@@ -62,20 +62,7 @@ private:
     bool m_needsTransformUpdate : 1;
 };
 
-inline RenderSVGViewportContainer* toRenderSVGViewportContainer(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isSVGViewportContainer());
-    return static_cast<RenderSVGViewportContainer*>(object);
-}
-
-inline const RenderSVGViewportContainer* toRenderSVGViewportContainer(const RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isSVGViewportContainer());
-    return static_cast<const RenderSVGViewportContainer*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderSVGViewportContainer(const RenderSVGViewportContainer*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderSVGViewportContainer, isSVGViewportContainer());
 
 } // namespace WebCore