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 [Inner content]']);
    expect(Scheduler).toFlushAndYield(['Inner content']);
    expect(ReactNoop.getChildren()).toEqual([
      span('Sync'),
      span('Outer content'),
      span('Inner content'),
    ]);
  });
  it('renders an expiration boundary synchronously', async () => {
    spyOnDev(console, 'error');
    
    ReactNoop.flushSync(() =>
      ReactNoop.render(
        <Fragment>
          <Suspense fallback={<Text text="Loading..." />}>
            <AsyncText text="Async" />
          </Suspense>
          <Text text="Sync" />
        </Fragment>,
      ),
    );
    expect(Scheduler).toHaveYielded([
      
      'Suspend! [Async]',
      
      'Loading...',
      
      'Sync',
    ]);