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.
const [count, updateCount] = useState('(empty)');
        useEffect(() => {
          Scheduler.unstable_yieldValue(`Schedule update [${props.count}]`);
          ReactNoop.flushSync(() => {
            updateCount(props.count);
          });
        }, [props.count]);
        return <Text text={'Count: ' + count} />;
      }
      act(() => {
        ReactNoop.render(<Counter count={0} />, () =>
          Scheduler.unstable_yieldValue('Sync effect'),
        );
        expect(Scheduler).toFlushAndYieldThrough([
          'Count: (empty)',
          'Sync effect',
        ]);
        expect(ReactNoop.getChildren()).toEqual([span('Count: (empty)')]);
        expect(() => {
          ReactNoop.flushPassiveEffects();
        }).toThrow('flushSync was called from inside a lifecycle method');
      });
    });
    it('unmounts previous effect', () => {
      function Counter(props) {