... because the latter are not meant to be modified from non-main thread
and especially after V8 isolate is set up while the former are modified
cuncurrently by tracing API.

Tbr: verwaest@chromium.org
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_rel
Bug: v8:8929, v8:8834
Change-Id: I44d3da2f388bb8bb8d0365ac6354e761bf92b936
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1505581Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60104}