* Support using id to cancel scheduled callback
**what is the change?:**
see title
**why make this change?:**
Once we support multiple callbacks you will need to use the id to
specify which callback you mean.
**test plan:**
Added a test, ran all tests, lint, etc.
* ran prettier
* fix lint
* Use object for storing callback info in scheduler
* Wrap initial test in a describe block
* Support multiple callbacks in `ReactScheduler`
**what is the change?:**
We keep a queue of callbacks instead of just one at a time, and call
them in order first by their timeoutTime and then by the order which
they were scheduled in.
**why make this change?:**
We plan on using this module to coordinate JS outside of React, so we
will need to schedule more than one callback at a time.
**test plan:**
Added a boatload of shiny new tests. :)
Plus ran all the old ones.
NOTE: The tests do not yet cover the vital logic of callbacks timing
out, and later commits will add the missing test coverage.
* Heuristic to avoid looking for timed out callbacks when none timed out
**what is the change?:**
Tracks the current soonest timeOut time for all scheduled callbacks.
**why make this change?:**
We were checking every scheduled callback to see if it timed out on
every tick. It's more efficient to skip that O(n) check if we know that
none have timed out.
**test plan:**
Ran existing tests.
Will write new tests to cover timeout behavior in more detail soon.
* Put multiple callback support under a disabled feature flag
**what is the change?:**
See title
**why make this change?:**
We don't have error handling in place yet, so should maintain the old
behavior until that is in place.
But want to get this far to continue making incremental changes.
**test plan:**
Updated and ran tests.
* Hide support for multiple callbacks under a feature flag
**what is the change?:**
see title
**why make this change?:**
We haven't added error handling yet, so should not expose this feature.
**test plan:**
Ran all tests, temporarily split out the tests for multiple callbacks
into separate file. Will recombine once we remove the flag.
* Fix nits from code review
See comments on https://github.com/facebook/react/pull/12743
* update checklist in comments
* Remove nested loop which calls additional timed out callbacks
**what is the change?:**
We used to re-run any callbacks which time out whilst other callbacks
are running, but now we will only check once for timed out callbacks
then then run them.
**why make this change?:**
To simplify the code and the behavior of this module.
**test plan:**
Ran all existing tests.
* Remove feature flag
**what is the change?:**
see title
**why make this change?:**
Because only React is using this, and it sounds like async. rendering
won't hit any different behavior due to these changes.
**test plan:**
Existing tests pass, and this allowed us to recombine all tests to run
in both 'test' and 'test-build' modes.
* remove outdated file
* fix typo