Fix bugs in DisplayNames v2

Bug: v8:12043
Change-Id: I0691387546ec82616bdf22d19c8a990c8164fca2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3071915


Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76147}