Avoid redundant zeros and ones in swizzle constructor.

Bug: skia:10721
Change-Id: Ib9e51b736bafb6e4493db4f50e9835fbd86c415d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/317247
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
4 files changed