-
-// 25.1.2.1.1 %IteratorPrototype%[@@iterator]()
-if ((!IS_PURE || NEW_ITERATOR_PROTOTYPE) && !has(IteratorPrototype, ITERATOR)) {
- createNonEnumerableProperty(IteratorPrototype, ITERATOR, returnThis);
+else if (IS_PURE) IteratorPrototype = create(IteratorPrototype);
+
+// `%IteratorPrototype%[@@iterator]()` method
+// https://tc39.es/ecma262/#sec-%iteratorprototype%-@@iterator
+if (!isCallable(IteratorPrototype[ITERATOR])) {
+ redefine(IteratorPrototype, ITERATOR, function () {
+ return this;
+ });