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 [counter, setCounter] = useState(0);
        const [_startTransition] = useTransition();
        startTransition = _startTransition;
        if (counter === 0) {
          startTransition(() => {
            setCounter(c => c + 1);
          });
        }
        return <Text text={counter} />;
      }
      const root = ReactNoop.createRoot();
      root.render(<App />);
      expect(Scheduler).toFlushAndYield([1]);
      expect(root).toMatchRenderedOutput(<span prop={1} />);
    });
  });
  describe('useReducer', () => {
    it('simple mount and update', () => {
      const INCREMENT = 'INCREMENT';
      const DECREMENT = 'DECREMENT';
      function reducer(state, action) {