The RTT type can not be used directly in WebAssembly any more and is treated
as a compiler-internal type for the GC MVP.

Bug: v8:7748
Change-Id: I97cb241e6c46446149cc6ae2b1d535b93402fa76
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3787877
Auto-Submit: Matthias Liedtke <mliedtke@chromium.org>
Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
Commit-Queue: Matthias Liedtke <mliedtke@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82000}