Add Bot-Commit label Copied from https://chrome-internal.googlesource.com/All-Projects/+/9babaf0609785a042fa3b22c3bbe6d4e381acb22/ Change-Id: I06c2ef50e087f620f9322e1845016af2b6d6a71e Reviewed-on: https://dart-review.googlesource.com/c/All-Projects/+/212828 Reviewed-by: William Hesse <whesse@google.com>