... behind --trace-zone-type-stats flag.

Per-object-type statistics requires the following GN args:
  v8_enable_precise_zone_stats = true
  use_rtti = true

When precise zone stats is enabled, the used zone memory value is
calculated more precisely, in particular it takes into account
the state of the active segment. By default, the used memory in
the active segment is not taken into account because of performance
overhead.

Bug: v8:10572
Change-Id: I938d9e264cfe6a8b63a89db87d187d8e2be63c8b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2281006
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68972}