Marking resets global handles which touches the corresponding slots on the
embedder side. The embedder may already have freed the memory which results in
use after free.

Bug: chromium:843903
Change-Id: I05a62f28d801b4de167f6fbf1be29743544c1293
Reviewed-on: https://chromium-review.googlesource.com/c/1296457Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56911}