Add MacBookAir jobs.

No-Try: true
Change-Id: I99f246687b8efc45068db18a3dc72162bdef178d
Reviewed-on: https://skia-review.googlesource.com/103080
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
5 files changed