Remove compiler feature detection for = delete

sky/engine/core/rendering/RenderMedia.h

Index: sky/engine/core/rendering/RenderMedia.h
diff --git a/sky/engine/core/rendering/RenderMedia.h b/sky/engine/core/rendering/RenderMedia.h
index bf4ff2d4e0d46c66554539b7d21a678530ae07e6..7abf503b5c8dd3ac5a0f2690c70e46cab51a3d12 100644
--- a/sky/engine/core/rendering/RenderMedia.h
+++ b/sky/engine/core/rendering/RenderMedia.h
@@ -42,8 +42,8 @@ public:
     RenderObject* lastChild() const { ASSERT(children() == virtualChildren()); return children()->lastChild(); }
 
     // If you have a RenderMedia, 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;
 
     const RenderObjectChildList* children() const { return &m_children; }
     RenderObjectChildList* children() { return &m_children; }