This is a reland of 3238162d

No changes since the last reland.

Original change's description:
> Reland "[heap] Add epoch to GC tracing events"
>
> This is a reland of be52501d
>
> Fix data race by not emitting the epoch for sweeper background jobs
> at them moment.
>
> Original change's description:
> > [heap] Add epoch to GC tracing events
> >
> > This CL adds the TRACE_GC_EPOCH macro, which adds the epoch as attribute
> > to the trace event. Use TRACE_GC_EPOCH for top-level events, nested
> > events can get the information from its parent.
> >
> > V8's GC needs an epoch for young and full collections, since scavenges
> > also occur during incremental marking. The epoch is also process-wide,
> > so different isolates do not reuse the same id.
> >
> > Change-Id: I8889bccce51e008374b4796445a50062bd87a45d
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2565247
> > Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
> > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#71521}
>
> Change-Id: Ib8f4bfdc01c459955eb6db63bb6e24a8aa068f09
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2567702
> Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#71567}

TBR=ulan@chromium.org,dinfuehr@chromium.org

Change-Id: I09dcfabbad4ef1ad50e02a227282982cd7d87997
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2571122Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71609}