fix a web incompatibility issue of Iterator helpers proposal

tc39/proposal-iterator-helpers#287

CHANGELOG.md

@@ -11,6 +11,7 @@
     - `Promise.withResolvers`
   - Moved to stable ES, [November 2023 TC39 meeting](https://twitter.com/robpalmer2/status/1729216597623976407)
   - Added `es.` namespace module, `/es/` and `/stable/` namespaces entries
+- Fixed a web incompatibility issue of [`Iterator` helpers proposal](https://github.com/tc39/proposal-iterator-helpers), [proposal-iterator-helpers/287](https://github.com/tc39/proposal-iterator-helpers/pull/287) and some following changes, November 2023 TC39 meeting
 - Added [`Uint8Array` to / from base64 and hex stage 2 proposal](https://github.com/tc39/proposal-arraybuffer-base64):
   - Methods:
     - `Uint8Array.fromBase64`

packages/core-js/modules/esnext.iterator.constructor.js

@@ -2,19 +2,24 @@
 var $ = require('../internals/export');
 var global = require('../internals/global');
 var anInstance = require('../internals/an-instance');
+var anObject = require('../internals/an-object');
 var isCallable = require('../internals/is-callable');
 var getPrototypeOf = require('../internals/object-get-prototype-of');
-var createNonEnumerableProperty = require('../internals/create-non-enumerable-property');
+var defineBuiltInAccessor = require('../internals/define-built-in-accessor');
+var createProperty = require('../internals/create-property');
 var fails = require('../internals/fails');
 var hasOwn = require('../internals/has-own-property');
 var wellKnownSymbol = require('../internals/well-known-symbol');
 var IteratorPrototype = require('../internals/iterators-core').IteratorPrototype;
+var DESCRIPTORS = require('../internals/descriptors');
 var IS_PURE = require('../internals/is-pure');
 
+var CONSTRUCTOR = 'constructor';
+var ITERATOR = 'Iterator';
 var TO_STRING_TAG = wellKnownSymbol('toStringTag');
 
 var $TypeError = TypeError;
-var NativeIterator = global.Iterator;
+var NativeIterator = global[ITERATOR];
 
 // FF56- have non-standard global helper `Iterator`
 var FORCED = IS_PURE
@@ -28,12 +33,27 @@ var IteratorConstructor = function Iterator() {
   if (getPrototypeOf(this) === IteratorPrototype) throw new $TypeError('Abstract class Iterator not directly constructable');
 };
 
-if (!hasOwn(IteratorPrototype, TO_STRING_TAG)) {
-  createNonEnumerableProperty(IteratorPrototype, TO_STRING_TAG, 'Iterator');
-}
+var defineIteratorPrototypeAccessor = function (key, value) {
+  if (DESCRIPTORS) {
+    defineBuiltInAccessor(IteratorPrototype, key, {
+      configurable: true,
+      get: function () {
+        return value;
+      },
+      set: function (replacement) {
+        anObject(this);
+        if (this === IteratorPrototype) throw new $TypeError("You can't redefine this property");
+        if (hasOwn(this, key)) this[key] = replacement;
+        else createProperty(this, key, replacement);
+      }
+    });
+  } else IteratorPrototype[key] = value;
+};
+
+if (!hasOwn(IteratorPrototype, TO_STRING_TAG)) defineIteratorPrototypeAccessor(TO_STRING_TAG, ITERATOR);
 
-if (FORCED || !hasOwn(IteratorPrototype, 'constructor') || IteratorPrototype.constructor === Object) {
-  createNonEnumerableProperty(IteratorPrototype, 'constructor', IteratorConstructor);
+if (FORCED || !hasOwn(IteratorPrototype, CONSTRUCTOR) || IteratorPrototype[CONSTRUCTOR] === Object) {
+  defineIteratorPrototypeAccessor(CONSTRUCTOR, IteratorConstructor);
 }
 
 IteratorConstructor.prototype = IteratorPrototype;