It seems like SP on heap does not produce too much memory fragmentation,
therefore we do not need UndoLastAllocationAt.

Bug: v8:11872
Change-Id: Id2e44405329b52c1dcd6cd81bfc72ffba00035ee
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3129428
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76581}