Some iwyu for tests which will otherwise break.

A change currently in progress would break these test files since they
aren't including what they use. Make them include what they use so they
don't break in the future.

Change-Id: I25d8d57631706dec0d0197b3759c6c18a0fe3aa0
Reviewed-on: https://skia-review.googlesource.com/114465
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
5 files changed