Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderWidget.h

Index: Source/core/rendering/RenderWidget.h
diff --git a/Source/core/rendering/RenderWidget.h b/Source/core/rendering/RenderWidget.h
index abbd6fc68b2bfd38821c49c78052bbd64460238d..b9ed0f9c4aae2eb13369dd1abe95c9de90ff9278 100644
--- a/Source/core/rendering/RenderWidget.h
+++ b/Source/core/rendering/RenderWidget.h
@@ -79,20 +79,7 @@ private:
     int m_refCount;
 };
 
-inline RenderWidget* toRenderWidget(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isWidget());
-    return static_cast<RenderWidget*>(object);
-}
-
-inline const RenderWidget* toRenderWidget(const RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isWidget());
-    return static_cast<const RenderWidget*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderWidget(const RenderWidget*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderWidget, isWidget());
 
 } // namespace WebCore