A switch can only produce a hole if it does not have fallthrough.
This actually only happens for SwitchOnGeneratorState bytecode.

We calculate the highest post dominating hole by traversing each
target.

Bug: v8:7700
Change-Id: Ia86ac08b1062dc48296e24beb95b3e3c3418ea6b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3826045
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82529}