The JSONTraceWriter didn't write the "flow_in", "flow_out" and "bind_id"
fields, which are necessary to support TRACE_EVENT_WITH_FLOW and
friends. This just mirrors the logic from trace_event_impl.cc in Chrome.

Bug: v8:8991
Change-Id: I496db587fbb74d3c7205bbab4c23ec41c63fa715
Document: http://bit.ly/v8-tracing-signals
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1521108Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60218}