[svg] Implement feDisplacementMap

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

Bug: skia:10841
Change-Id: Icf1a560b2d83e7954207fb1740e77193362b9fd4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/356312
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 71c161f..f7fc6c9 100644
--- a/modules/svg/include/SkSVGNode.h
+++ b/modules/svg/include/SkSVGNode.h
@@ -28,6 +28,7 @@
     kFeBlend,
     kFeColorMatrix,
     kFeComposite,
+    kFeDisplacementMap,
     kFeFlood,
     kFeGaussianBlur,
     kFeMorphology,