Remove use of SkMatrixProvider in SkShaderBase::appendRootStages

Towards getting rid of SkMatrixProvider in favor of just using CTM
SkMatrices.

Bug: skia:14076
Change-Id: I6b6e0c11155ca72b6e4e7fe84e0edbb05dee34d9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/635083
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
8 files changed