Remove compiler feature detection for = delete

sky/engine/core/rendering/RenderInline.h

Index: sky/engine/core/rendering/RenderInline.h
diff --git a/sky/engine/core/rendering/RenderInline.h b/sky/engine/core/rendering/RenderInline.h
index b62f7a2ef9308741b5700f17b9663d81aa8c0620..6696c1dd43a6fcfdf0ff9c9c6a8e33494987ffdd 100644
--- a/sky/engine/core/rendering/RenderInline.h
+++ b/sky/engine/core/rendering/RenderInline.h
@@ -41,8 +41,8 @@ public:
     RenderObject* lastChild() const { ASSERT(children() == virtualChildren()); return children()->lastChild(); }
 
     // If you have a RenderInline, use firstChild or lastChild instead.
-    void slowFirstChild() const WTF_DELETED_FUNCTION;
-    void slowLastChild() const WTF_DELETED_FUNCTION;
+    void slowFirstChild() const = delete;
+    void slowLastChild() const = delete;
 
     virtual void addChild(RenderObject* newChild, RenderObject* beforeChild = 0) override;