Lock the mutex of PagedSpace before invoking FreeLinearAllocationArea().

Bug: v8:10315
Change-Id: If96b9b8b72932590daf3d548be41c20796ed524f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2367857Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69515}