Remove compiler feature detection for = delete

sky/engine/core/editing/PlainTextRange.h

Index: sky/engine/core/editing/PlainTextRange.h
diff --git a/sky/engine/core/editing/PlainTextRange.h b/sky/engine/core/editing/PlainTextRange.h
index e9ad645c769da6f4d2e2037c20cd828148225fcc..8c8c9779202ab6a099153bcda88ba955d07bacbd 100644
--- a/sky/engine/core/editing/PlainTextRange.h
+++ b/sky/engine/core/editing/PlainTextRange.h
@@ -54,7 +54,7 @@ public:
     static PlainTextRange create(const ContainerNode& scope, const Range&);
 
 private:
-    PlainTextRange& operator=(const PlainTextRange&)  WTF_DELETED_FUNCTION;
+    PlainTextRange& operator=(const PlainTextRange&)  = delete;
 
     enum GetRangeFor { ForGeneric, ForSelection };
     PassRefPtrWillBeRawPtr<Range> createRangeFor(const ContainerNode& scope, GetRangeFor) const;