message: refactor(service-worker): remove unused variables and imports from tests
  This commit removes some unused variables (and associated imports) from
  `integration_spec.ts`.
  PR Close
diff: import {NgswCommChannel} from '@angular/service-worker/src/low_level';
  import {SwPush} from '@angular/service-worker/src/push';
  import {SwUpdate} from '@angular/service-worker/src/update';
  -import {MockServiceWorkerContainer, MockServiceWorkerRegistration} from '@angular/service-worker/testing/mock';
  +import {MockServiceWorkerContainer} from '@angular/service-worker/testing/mock';
  import {CacheDatabase} from '@angular/service-worker/worker/src/db-cache';
  import {Driver} from '@angular/service-worker/worker/src/driver';
  import {Manifest} from '@angular/service-worker/worker/src/manifest';
  @@ -78,7 +78,6 @@ const serverUpdate =
  describe('ngsw + companion lib', () => {
  let mock: MockServiceWorkerContainer;
  let comm: NgswCommChannel;
  - let reg: MockServiceWorkerRegistration;
  let scope: SwTestHarness;
  let driver: Driver;
  @@ -102,7 +101,6 @@ describe('ngsw + companion lib', () => {
  });
  mock.setupSw();
  - reg = mock.mockRegistration!;
  await Promise.all(scope.handleFetch(new MockRequest('/only.txt'), 'default'));
  await driver.initialized;
  @@ -117,9 +115,7 @@ describe('ngsw + companion lib', () => {
  const update = new SwUpdate(comm);
  scope.updateServerState(serverUpdate);
  - const gotUpdateNotice = (async () => {
  - const notice = await obsToSinglePromise(update.available);
  - })();
  + const gotUpdateNotice = (async () => await obsToSinglePromise(update.available))();
  await update.checkForUpdate();
  await gotUpdateNotice;
  