message: Remove an old (and ineffectual) perf workaround
diff: @@ -168,16 +168,5 @@ export function extendIfUndefined<T>(base: MapLike<T>, extension: MapLike<T> | u
  // Create a MapLike with good performance.
  export function createMap<T>(): MapLike<T> {
  - const map = Object.create(null);
  -
  - // Using 'delete' on an object causes V8 to put the object in dictionary mode.
  - // This disables creation of hidden classes, which are expensive when an object is
  - // constantly changing shape.
  - // eslint-disable-next-line @typescript-eslint/dot-notation
  - map["__"] = undefined;
  - // eslint-disable-next-line @typescript-eslint/dot-notation, @typescript-eslint/no-dynamic-delete
  - delete map["__"];
  -
  - // eslint-disable-next-line @typescript-eslint/no-unsafe-return
  - return map;
  + return Object.create(null) as MapLike<T>;
  }
  