The TurboFan events, like time in register allocation, are only
interesting in special cases, but create lots of events. Therefore it is
good to put these events into their own tracing category.

Bug: chromium:1084929
Change-Id: I971badc1ff58f99bd57b2ddfc93b625b356d6a2d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2595436Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71830}