This is a stop-gap solution (while we wait for a proper spec)
that lets managed WasmGC objects perform round-trips through
JavaScript. On the JavaScript side, they appear as empty/opaque.

Bug: v8:7748
Change-Id: I0dd368bc14d622f3ef41871484228267359e9b5b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2316306
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69207}