I think those are safe to keep and add useful information to highlight
the type of evacuate copy step being performed.

This is a prerequisite for https://chromium-review.googlesource.com/c/v8/v8/+/934263
as it will drop tracing individual work items and will
leave it to top-level item trace events like these to
highlight individual work item's work.

Will reland after reverting them all however to confirm the re-adding
these doesn't cause regressions as the fine grain trace events
initially did.

R=hpayer@chromium.org

Bug: chromium:813824
Change-Id: I8e53b880ce0aeae08afa7a2c0f36a455f645bcfa
Reviewed-on: https://chromium-review.googlesource.com/934248Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51543}