Convert argument list contributor tests

Change-Id: I998bc7a23e83541b10c38596f66a7496fb3d9682
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/307974
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: bwilkerson