GrMatrixConvolutionEffect uses child for sampled kernel

Bug: skia:10139

Change-Id: Ic1380cf47c9293a54bf104ccbb3ca3222e704276
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/296127
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Adlai Holler <adlai@google.com>
2 files changed