Allow for non opaque colors for src-over lcd fallback case in gpu

Since skia is currently requiring the dst to be opaque for lcd draws this
change is safe to make in terms of correctly. It will also be faster than
the current shader based blending.

Bug: chromium:725879
Change-Id: I0c14b80eb5ab819500afc55030df83d5ddbef94a
Reviewed-on: https://skia-review.googlesource.com/17840
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
1 file changed