Decal fallback for SkImageShader

Bug: skia:
Change-Id: Ib39f74886c0edc655ded8ba1075e5205361ae650
Reviewed-on: https://skia-review.googlesource.com/c/176225
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
12 files changed