Loop analysis never visited nodes whose marks happened to not change
when visiting their outputs in backwards propagation. This CL ensures
that each reachable node is visited at least once.

Change-Id: I70cd73737c0abe8151d5e23bc50525599fa3ea6a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2581538Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71938}