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 [state, setState] = React.useState(false);
          Scheduler.unstable_yieldValue('Parent');
          return <Child setState={setState} state={state} />;
        }
        function Child({setState, state}) {
          Scheduler.unstable_yieldValue('Child');
          React.useEffect(() => {
            Scheduler.unstable_yieldValue('Child passive create');
            return () => {
              Scheduler.unstable_yieldValue('Child passive destroy');
              setState(true);
            };
          }, []);
          return state;
        }
        act(() => {
          ReactNoop.renderToRootWithID(<Parent />, 'root');
          expect(Scheduler).toFlushAndYieldThrough([
            'Parent',
            'Child',
            'Child passive create',
          ]);
          
          ReactNoop.unmountRootWithID('root');
          expect(Scheduler).toFlushAndYield(['Child passive destroy']);
        });
      });
    }
    it('updates have async priority', () => {
      function Counter(props) {