add a test that sRGB stages round trip

Change-Id: Ide8303f6fc162f3703f7db298fe210d47225a580
Reviewed-on: https://skia-review.googlesource.com/16988
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed