Improve tests/comments, to prepare for calling functions before definition

Bug: skia:12137
Change-Id: I609dd2578bf39a30e036ea85281886f8c4554579
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/431038
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
5 files changed