We can't create Refs inside a DisallowGarbageCollection scope since
the MapData constructor uses a parking mutex (which may park the local
heap and let GC run).

Bug: v8:11957, v8:7790
Change-Id: I300b76a15f0f63514ca049f78099e1e6125a6569
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3010281Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75609}