Sandbox: https://codesandbox.io/s/cranky-kapitsa-op3jh

Repro: type "a" and then after a second "b"

Expected: Eventually you'll see "ab" in all fields. Pending "..." indicator goes away.

Actual: You'll keep seeing "a" in low pri field. Pending "..." indicator is stuck.
() => Scheduler.unstable_yieldValue('Sync effect'),
          );
          expect(Scheduler).toFlushAndYieldThrough([
            'Component',
            'a:layout create',
            'Sync effect',
          ]);
          ReactNoop.flushPassiveEffects();
          expect(Scheduler).toHaveYielded([
            'a:passive create',
            'b:passive create',
          ]);
          
          ReactNoop.unmountRootWithID('root');
          expect(Scheduler).toFlushAndYieldThrough(['a:layout destroy']);
          
          expect(completePendingRequest).toErrorDev(
            "Warning: Can't perform a React state update on an unmounted component.",
          );
        });
      });
      it('still warns if there are updates after pending passive unmount effects have been flushed', () => {
        let updaterFunction;
        function Component() {
          Scheduler.unstable_yieldValue('Component');
          const [state, setState] = React.useState(false);
          updaterFunction = setState;
          React.useEffect(() => {
            Scheduler.unstable_yieldValue('passive create');
            return () => {