Remove compiler feature detection for = delete

sky/engine/core/rendering/RenderBox.h

Index: sky/engine/core/rendering/RenderBox.h
diff --git a/sky/engine/core/rendering/RenderBox.h b/sky/engine/core/rendering/RenderBox.h
index f304e44783e541241b596ad9d9740fcdcfc42306..9f50453f4e8c8ad179c61da251365b7896c02631 100644
--- a/sky/engine/core/rendering/RenderBox.h
+++ b/sky/engine/core/rendering/RenderBox.h
@@ -718,7 +718,7 @@ private:
 
     virtual InvalidationReason invalidatePaintIfNeeded(const PaintInvalidationState&, const RenderLayerModelObject& newPaintInvalidationContainer) override final;
 
-    bool isBox() const WTF_DELETED_FUNCTION; // This will catch anyone doing an unnecessary check.
+    bool isBox() const = delete; // This will catch anyone doing an unnecessary check.
 
     // The width/height of the contents + borders + padding.  The x/y location is relative to our container (which is not always our parent).
     LayoutRect m_frameRect;