antialias matrix-image-filter to get smooth diagonals

src/core/SkMatrixImageFilter.h

Index: src/core/SkMatrixImageFilter.h
diff --git a/src/core/SkMatrixImageFilter.h b/src/core/SkMatrixImageFilter.h
index 012a36057da3048dca081362bfeea461ec05454f..1f556856287712a1e008558370dce2212d6cbee7 100644
--- a/src/core/SkMatrixImageFilter.h
+++ b/src/core/SkMatrixImageFilter.h
@@ -57,6 +57,8 @@ protected:
                                 SkIRect* dst) const override;
 
 private:
+    bool onMayDrawWithMatrix() const override { return true; }
+
     SkMatrix              fTransform;
     SkFilterQuality       fFilterQuality;
     typedef SkImageFilter INHERITED;