Stacked on #34481.
We currently track the suspended state temporarily with a global which
is safe as long as we always read it during a sync pass. However, we
sometimes read it in closures and then we have to be carefully to pass
the right one since it's possible another commit on a different root has
started at that point. This avoids this footgun.
Another reason to do this is that I want to read it in
`startViewTransition` which is in an async gap after which point it's no
longer safe. So I have to pass that through the `commitRoot` bound
function.
5d49b2b7f4