This delays removing dead loop's loop exits after we iterate all uses of
the loop. That way, we avoid mutating the use collection while iterating
it.
Bug: chromium:803022
Change-Id: I17462dd82c3cb78f2f630e5db81d8ccdcc517d83
Reviewed-on: https://chromium-review.googlesource.com/878329
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50813}
