Revert "Make textures used with alpha-only color-types produce 0s for RGB"

This reverts commit 16d86135b739bc89ec4744bcec3eccc590c433ba.

No-Tree-Checks: true
Change-Id: Ia5ba78259a3a406c4c0f8ddca9aaf495d29b34f8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/348176
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
19 files changed