[vm/runtime] Support tracing of subtype checks in runtime.
[vm/runtime] Support tracing of subtype checks in runtime.

TEST=for debugging only

Change-Id: I9780e0374750b044613a654043342925eb904a17
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/199362
Reviewed-by: Alexander Markov <239e774fd29abc1267878f57afe1a8a03e0ca887@google.com>
Commit-Queue: Régis Crelier <c2bf536a10d9f2530c38e4e8da517718be8c39ce@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk