Use a read-write lock for protecting original_top, original_limit and
pending_object for all spaces. This way Heap::IsPendingAllocation is
always guaranteed to read a consistent top/limit-pair and also the
last values for those fields.

The main thread will acquire an exclusive lock to update those fields.
Concurrent Turbofan threads will use shared locks to read them.

This may be quite expensive on the Turbofan-side, so landing this CL
should help us figure out how big of a regression this simple fix would
be. For main thread execution performance is supposed to be okay, since
this is only used on the allocation slow path.

Bug: v8:11778, chromium:1213266
Change-Id: I9464f53fd50057ec2540ab5b79f74ee52a5d7500
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2903143
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74814}