This adds a non-standard, unsafe instruction for performance
experiments: ref.cast_nop_static behaves like ref.cast_static
as far as static types are concerned, but emits no code.

Bug: v8:7748
Change-Id: Ic5797a941146a06d7c6ff249d8e29919145d8ea1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3639206Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80471}