[svg] Implement feMorphology filter

https://www.w3.org/TR/SVG11/filters.html#feMorphologyElement

Bug: skia:10841
Change-Id: I0b0028fb815c490670f9f1e888770efb194a8f3b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/356107
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Tyler Denniston <tdenniston@google.com>
diff --git a/modules/svg/include/SkSVGNode.h b/modules/svg/include/SkSVGNode.h
index 28b21c3..71c161f 100644
--- a/modules/svg/include/SkSVGNode.h
+++ b/modules/svg/include/SkSVGNode.h
@@ -30,6 +30,7 @@
     kFeComposite,
     kFeFlood,
     kFeGaussianBlur,
+    kFeMorphology,
     kFeOffset,
     kFeTurbulence,
     kFilter,