[sksg] Add 3x3 Concat Transform specialization

When both inputs are 3x3, use 3x3 Concat.

TBR=
Change-Id: Ife6a98792c2ed57a2a987fe5d0bdf265aeb64b0a
Reviewed-on: https://skia-review.googlesource.com/c/182968
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
diff --git a/modules/sksg/src/SkSGGeometryTransform.cpp b/modules/sksg/src/SkSGGeometryTransform.cpp
index f338236..2602a46 100644
--- a/modules/sksg/src/SkSGGeometryTransform.cpp
+++ b/modules/sksg/src/SkSGGeometryTransform.cpp
@@ -37,7 +37,7 @@
 
     // We don't care about matrix reval results.
     fTransform->revalidate(ic, ctm);
-    const auto m = TransformPriv::AsMatrix(fTransform);
+    const auto m = TransformPriv::As<SkMatrix>(fTransform);
 
     auto bounds = fChild->revalidate(ic, ctm);
     fTransformedPath = fChild->asPath();