[svg] Implement feBlend filter

Note we are still not passing filters-blend-01-b because we don't yet
support feImage.

Bug: skia:10841
Change-Id: Ibca52c0e8e8d45e73473dea3b0252d6b81eaa584
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/354657
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 263a037..28b21c3 100644
--- a/modules/svg/include/SkSVGNode.h
+++ b/modules/svg/include/SkSVGNode.h
@@ -25,6 +25,7 @@
     kClipPath,
     kDefs,
     kEllipse,
+    kFeBlend,
     kFeColorMatrix,
     kFeComposite,
     kFeFlood,