Fix SkLocalMatrixShader::isAImage() to respect local matrix and image local matrix

Fixes cts tests.

b/37161109
b/37237678

CQ_INCLUDE_TRYBOTS=skia.primary:Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Debug-MSAN

Bug: skia:
Change-Id: I438b8b17f4c7c5bfcb50dfa22af1ddb97b905088
Reviewed-on: https://skia-review.googlesource.com/13261
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Matt Sarett <msarett@google.com>
4 files changed