This fixes two issues:
- labs resetting didn't account bytes as beeing freed;
- large object were not accounted.

The CL introduces a single bottleneck for labs resetting in
ObjectAllocator, which is aware of StatsCollector. This way
NormalSpace is treated as a value object and all invariants
are maintained by ObjectAllocator (and Sweeper).

Bug: chromium:1056170
Change-Id: I027cc01fe5028a3dfa81905d7ea53dd12d1c1f20
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2237629
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68286}