So far this is mainly a readability improvement to specify
expectations on the packed argument. In the future we should also
check signedness during bytecode generation.

Drive-by: Update DCHECK to allow signed args to
CHECK_CURRENT_POSITION.

Bug: chromium:1083450
Change-Id: I9376ec691b51eb251c972309ad65dd6c04eec3ae
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2207137
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67880}