Make dstreadshuffle GM more visually comprehensible

Change-Id: I1f42f474fb753e3dfbb574864f0279f139dce7e9
Reviewed-on: https://skia-review.googlesource.com/9732
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
1 file changed