Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderEmbeddedObject.h

Index: Source/core/rendering/RenderEmbeddedObject.h
diff --git a/Source/core/rendering/RenderEmbeddedObject.h b/Source/core/rendering/RenderEmbeddedObject.h
index cc49411bc07f22e029e6163b7de6e53f8b8c2122..28b582d7d7ace4a7491d8b397f62d82af0d1bc9f 100644
--- a/Source/core/rendering/RenderEmbeddedObject.h
+++ b/Source/core/rendering/RenderEmbeddedObject.h
@@ -88,14 +88,7 @@ private:
     RenderObjectChildList m_children;
 };
 
-inline RenderEmbeddedObject* toRenderEmbeddedObject(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isEmbeddedObject());
-    return static_cast<RenderEmbeddedObject*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderEmbeddedObject(const RenderEmbeddedObject*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderEmbeddedObject, isEmbeddedObject());
 
 } // namespace WebCore