Revert "Don't flatten images in SkImageShader"

This reverts commit 318afe66e699970ebf789718b5a2297f783ed712.

Reason for revert: breaking Android roller due to failed CTS tests when drawing content from different colorspaces

Original change's description:
> Don't flatten images in SkImageShader
> 
> Bug: skia:9570
> 
> Change-Id: Idd4485b5c5814501fe98fbf2115d89a80a41f5c7
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/299139
> Commit-Queue: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Michael Ludwig <michaelludwig@google.com>

TBR=bsalomon@google.com,michaelludwig@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: skia:9570
Change-Id: I25af1062fb75a8353dd7b7dbb174eb06fa5b24fb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/299676
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
3 files changed