We were overwriting the shift Register, instead, we should be using the
tmp_shift register.

Bug: chromium:1242689
Change-Id: I732c9c1f8a43401ce003b22893db9e39dfac3817
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3116115
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76466}