Even though this is not a perfect protection, it will make it harder to
write to the wasm code space because it's not permanently RWX.
After optimizations (see https://crbug.com/v8/11974) the performance is
good enough that it's worth just enabling it.

R=ahaas@chromium.org

Bug: v8:11974
Change-Id: I82786e932387732863c3c5e3aa743f7836cc45e4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3464035Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79109}