We should also be able to test for larger examples, so this CL adds
support for directories where all files are included. If the directory
contains a .packages file that is used so we can test packages too.
Change-Id: Iceda03505575bd9e5604a6e374b7f5fa7185a82e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/111421
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>