... by combining generational and marking write barriers in one loop.

Bug: v8:7703
Change-Id: I825d530040d3f39143dd2d051dc5a9916e2f2997
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1611541Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61487}