dillon1000/react

Check for infinite update loops even if unmounted (#24697)

* [FORKED] Check for infinite update loops even if unmounted

The infinite update loop check doesn't need to run if the component
already unmounted, because an update to an unmounted component can't
cause a re-render. But because we used to run the check in this case,
anyway, I found one test in www that happens to "rely on" this behavior
(accidentally). The test is a pretty messy snapshot thing that I have no
interest fixing so to unblock the sync I'm just going to switch this
back to how it was.

* Add previous commit to forked revisions