Allow bytecodes processed by maglev to access the on-stack closure
register.

Bug: v8:7700
Change-Id: I757d0c1734ef478e5b9671ed87a4691101b4e29d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3506444
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79383}