Make GrTexture caching for SkPromiseImageTexture work when same texture
fulfills a different SkImage.

Bug: skia:8613
Change-Id: I7ee14112c69f8aaef223a37dda455259b501a2bf
Reviewed-on: https://skia-review.googlesource.com/c/184440
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
9 files changed