Update test_process and test_descriptor
Update test_process and test_descriptor

Switch from using `_tag` naming to `_rev` since Dart team packages
should be synced by commit before publishing and tagging.

Change-Id: Idfa571e89d434fa71b868b1b4b816f54310ca642
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/210948
Auto-Submit: Nate Bosch <dc212c74d8afde9c690fdd09e74d3e5c5d5a3de0@google.com>
Reviewed-by: Kevin Moore <1d6e7d10d051cf619c5282da3c28fd8d3e0a65a4@google.com>
Commit-Queue: Nate Bosch <dc212c74d8afde9c690fdd09e74d3e5c5d5a3de0@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