feat: typescript 2.9 support (#24652)

PR Close #24652

packages/core/src/util.ts

@@ -6,10 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-// Import zero symbols from zone.js. This causes the zone ambient type to be
-// added to the type-checker, without emitting any runtime module load statement
-import {} from 'zone.js';
-
 // TODO(jteplitz602): Load WorkerGlobalScope from lib.webworker.d.ts file #3492
 declare var WorkerGlobalScope: any /** TODO #9100 */;
 // CommonJS / Node have global context exposed as "global" variable.