Lift GrRenderTargetContext::rescale to GrSufaceContext

Bug: skia:9269
Change-Id: I7179c298f7b5ae580889d8fa7e3821fb2408aaad
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/229077
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
4 files changed