working around breakage related to zone.js loaded before core-js, close #953

Author: zloirock

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## Changelog
 ##### Unreleased
+- Worked around breakage related to `zone.js` loaded before `core-js`, [#953](https://github.com/zloirock/core-js/issues/953)
 - Added NodeJS 16.4 -> Chrome 91 compat data mapping
 
 ##### 3.15.1 - 2021.06.23

packages/core-js/modules/es.promise.js

@@ -55,7 +55,8 @@ var SUBCLASSING = false;
 var Internal, OwnPromiseCapability, PromiseWrapper, nativeThen;
 
 var FORCED = isForced(PROMISE, function () {
-  var GLOBAL_CORE_JS_PROMISE = inspectSource(PromiseConstructor) !== String(PromiseConstructor);
+  var PROMISE_CONSTRUCTOR_SOURCE = inspectSource(PromiseConstructor);
+  var GLOBAL_CORE_JS_PROMISE = PROMISE_CONSTRUCTOR_SOURCE !== String(PromiseConstructor);
   // V8 6.6 (Node 10 and Chrome 66) have a bug with resolving custom thenables
   // https://bugs.chromium.org/p/chromium/issues/detail?id=830565
   // We can't detect it synchronously, so just check versions
@@ -65,7 +66,7 @@ var FORCED = isForced(PROMISE, function () {
   // We can't use @@species feature detection in V8 since it causes
   // deoptimization and performance degradation
   // https://github.com/zloirock/core-js/issues/679
-  if (V8_VERSION >= 51 && /native code/.test(PromiseConstructor)) return false;
+  if (V8_VERSION >= 51 && /native code/.test(PROMISE_CONSTRUCTOR_SOURCE)) return false;
   // Detect correctness of subclassing with @@species support
   var promise = new PromiseConstructor(function (resolve) { resolve(1); });
   var FakePromise = function (exec) {