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(() => {
            
            
            updateCount(props.count);
            updateCount(props.count);
            updateCount(props.count);
            updateCount(props.count);
            updateCount(props.count);
            updateCount(props.count);
          }, [props.count]);
          return <Text text={'Count: ' + count} />;
        }
        act(() => {
          ReactNoop.renderLegacySyncRoot(<Counter count={0} />);
          
          expect(Scheduler).toFlushAndYieldThrough(['Count: (empty)']);
          expect(ReactNoop.getChildren()).toEqual([span('Count: (empty)')]);
        });
        
        
        
        expect(Scheduler).toHaveYielded(['Count: 0']);
        expect(ReactNoop.getChildren()).toEqual([span('Count: 0')]);
      },
    );
    it('flushSync is not allowed', () => {
      function Counter(props) {