This updates the downloaded version of unittest to commit
b91cfacaa05fa489dd88ae0040682c4459ac3662 in the dart-lang/test repository.
Bug:
Change-Id: Ibc285ea62f9267ca8cff8a63e3840648f5325f23
Reviewed-on: https://dart-review.googlesource.com/11062
Reviewed-by: William Hesse <whesse@google.com>
Reviewed-by: Bob Nystrom <rnystrom@google.com>
Commit-Queue: William Hesse <whesse@google.com>