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.
useEffect(() => {
          Scheduler.unstable_yieldValue(`Passive effect`);
        }, []);
        return <Text text="Passive" />;
      }
      const passive = <PassiveEffect key="p" />;
      act(() => {
        ReactNoop.render([<LayoutEffect key="l" />, passive]);
        expect(Scheduler).toFlushAndYieldThrough([
          'Layout',
          'Passive',
          'Layout effect',
        ]);
        expect(ReactNoop.getChildren()).toEqual([
          span('Layout'),
          span('Passive'),
        ]);
        
        
        ReactNoop.render([passive]);
        expect(Scheduler).toFlushAndYield(['Passive effect']);
        expect(ReactNoop.getChildren()).toEqual([span('Passive')]);
      });
      
      expect(Scheduler).toHaveYielded([]);
    });
    it('flushes passive effects even if siblings schedule an update', () => {
      function PassiveEffect(props) {