Repro: https://codesandbox.io/s/fast-water-4i4jb

Notice the flash. I'd expect `suspended` to be `true` during the high pri render.
expect(Scheduler).toHaveYielded(['Promise resolved [A]']);
      expect(Scheduler).toFlushAndYield(['A']);
      expect(ReactNoop.getChildren()).toEqual([span('A')]);
      
      React.unstable_withSuspenseConfig(
        () => ReactNoop.render(<App page="B" />),
        SUSPENSE_CONFIG,
      );
      expect(Scheduler).toFlushAndYield(['Suspend! [B]', 'Loading...']);
      Scheduler.unstable_advanceTime(1000);
      await advanceTimers(1000);
      
      expect(ReactNoop.getChildren()).toEqual([span('A')]);
      Scheduler.unstable_advanceTime(1100);
      await advanceTimers(1100);
      
      expect(ReactNoop.getChildren()).toEqual([
        hiddenSpan('A'),
        span('Loading...'),
      ]);
      
      Scheduler.unstable_advanceTime(3000);
      await advanceTimers(3000);
      expect(Scheduler).toHaveYielded(['Promise resolved [B]']);
      expect(Scheduler).toFlushAndYield(['B']);
      expect(ReactNoop.getChildren()).toEqual([span('B')]);
    });
    it('hooks', async () => {
      let transitionToPage;
      function App() {