pass sprite opacity to color xform when blitting.

This should be a mild optimization, avoiding an unpremul step
when we need to transform color spaces.

I didn't check anything beyond that
  1) we do hit this case
  2) there were no diffs for {8888 srgb gbr-8888 p3-8888 narrow}

Change-Id: I2f726f6ca0225990612a2f6af4a1d94c7c3a4ea8
Reviewed-on: https://skia-review.googlesource.com/147102
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed