fix(core): improve global variable detection (#28679)

Closes #16545

PR Close #28679

packages/core/test/util/global_spec.ts

@@ -0,0 +1,25 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {global} from '../../src/util/global';
+
+// Not yet available in TypeScript: https://github.com/Microsoft/TypeScript/pull/29332
+declare var globalThis: any /** TODO #9100 */;
+
+{
+  describe('global', () => {
+    it('should be global this value', () => {
+      const _global = new Function('return this')();
+      expect(global).toBe(_global);
+    });
+
+    if (typeof globalThis !== 'undefined') {
+      it('should use globalThis as global reference', () => { expect(global).toBe(globalThis); });
+    }
+  });
+}