Since snapshotting returns a vector of code pointers, we should add them
so the surrounding {WasmCodeRefScope}, to make sure that they are not
being garbage-collected while the serializer reads them.
This is unlikely to happen, since serialization is only triggered once
top-tier compilation is finished, and we usually do not garbage-collect
top-tier code, but in rare circumstances (e.g. in debugging), it could
theoretically happen.

R=ahaas@chromium.org

Change-Id: Ie1a9654a8a1467c12e42181776cec1dad7366036
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2644944Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72284}