The first pass in loop-unrolling aims to process stack check and loop
exit nodes. These nodes are all connected in a known fashion to the loop
header, so there is no need to traverse the whole loop.

Bug: v8:11298
Change-Id: I8336290ce7dddc8967f3fe05d3064b681c1e5c5a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2732007Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73166}