dillon1000/react

Use requestIdleCallback timeout to force expiration (#11548)

* Don't call idle callback unless there's time remaining

* Expiration fixture

Fixture that demonstrates how async work expires after a certain interval.
The fixture clogs the main thread with animation work, so it only works if the
`timeout` option is provided to `requestIdleCallback`.

* Pass timeout option to requestIdleCallback

Forces `requestIdleCallback` to fire if too much time has elapsed, even if the
main thread is busy. Required to make expiration times work properly. Otherwise,
async work can expire, but React never has a chance to flush it because the
browser never calls into React.