The 32-bit value is zero-extended to pointer size, which is a no-op on
32-bit systems. The operation changes nothing about the signedness of
the value, so the old name was a bit misleading.

We also provide one unified no-op implementation for all 32-bit systems.

R=thibaudm@chromium.org

Bug: v8:10949, chromium:1281995
Change-Id: Id04641fe793155ea98bf878b6789e4afce3da7df
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3424493Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78881}