clean up non-ASCII comments

Change-Id: I07ad00133f6a938de70a94024a0ebe36c6c542bb
Reviewed-on: https://skia-review.googlesource.com/6524
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Hal Canary <halcanary@google.com>
7 files changed