[maglev] Allow closure register to be loaded

Context:
https://chromium-review.googlesource.com/c/v8/v8/+/3506444

Bug: v8:7700
Change-Id: Ie877f7f18759f286597f07412ceb1ba25eb4787a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3512793


Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79416}