Remove color space restrictions from GrBackendTextureImageGenerator

This restriction should have only been enforced in linear-blending mode,
and even then, it's no longer true.

Fixes https://github.com/flutter/flutter/issues/14077

Bug: skia:
Change-Id: Ie0904475e29b213ad7995b8f39c02f6ea7396a9a
Reviewed-on: https://skia-review.googlesource.com/94782
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed