ref.cast_nop is used for internal testing only.
0xfb48 will become ref.test null.

Bug: v8:7748
Change-Id: Iaee762dd97a993a361edddf656090210876178a2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3913205Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Auto-Submit: Matthias Liedtke <mliedtke@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83430}