Currently, we assume:
  allocated-object-size = marked-bytes-on-previous-cycle + k,
which is not the case for the sticky bits (with the young generation
enabled). The CL introduces a variable
StatsCollector::marked_bytes_so_far_ that keeps track of marked bytes
across GCs.

Bug: chromium:1029379
Change-Id: I749c8c0174889c10093c75f88c096c68905bf36e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3545167Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79588}