tearDown() {
    clock.uninstall();
    stubs.reset();

    waitForTimeout(/**
                      @suppress {visibility} suppression added to enable type
                      checking
                    */
                   () => {
                     // Pointless assertion to verify that tearDown methods can
                     // contain waits.
                     assertTrue(testCase.now() >= testCase.startTime_);
                   },
                   0);
  }
Uninstalls the mock clock if it was installed, and restores the Step
timeout functions to the default window implementations.