[svg] Implement feColorMatrix filter

Supporting this filter will also allow us to start implementing and
testing the filter result DAG via the filters-color-01-b test. That test
is one of the simplest that involves filter result storage, so it's a
good candidate to start with.

Bug: skia:10841
Change-Id: Id8317ccfb78031cc6af83c9f3e3f382dcb6dee98
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/332599
Commit-Queue: Tyler Denniston <tdenniston@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
diff --git a/modules/svg/include/SkSVGNode.h b/modules/svg/include/SkSVGNode.h
index 73e051b..b2529a7 100644
--- a/modules/svg/include/SkSVGNode.h
+++ b/modules/svg/include/SkSVGNode.h
@@ -25,6 +25,7 @@
     kClipPath,
     kDefs,
     kEllipse,
+    kFeColorMatrix,
     kFeTurbulence,
     kFilter,
     kG,