IWYU for test files starting with 'B'.

Found reproduction of iwyu issue #486, fixed at
https://github.com/include-what-you-use/include-what-you-use/pull/522

Change-Id: Ic77a1a0c3b02b7853517c7fc4d98d92b29c2b0eb
Reviewed-on: https://skia-review.googlesource.com/113214
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
8 files changed