Data race access to chunk_map_. The main thread can read the map
while the background thread (concurrent SP compiler) adds a new page
to the map.

Bug: v8:12054
Change-Id: Ie7c596f3d3aeb4dca9cc6f41ed16f39dcafc7871
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3256547
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77654}