Use infix syntax from skvm

Nothing should draw differently, just wanting to make the code
more readable.

Change-Id: I139f673cd7b28536e91cb2a3c793c86c5fb143cc
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/280819
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
9 files changed