Add SMIL deprecation warning

Source/core/frame/UseCounter.cpp

Index: Source/core/frame/UseCounter.cpp
diff --git a/Source/core/frame/UseCounter.cpp b/Source/core/frame/UseCounter.cpp
index 33bafef013b2aea137be946057d0acf01259e2fc..5944c27c0bbac43a6de4d1443a5fcea6a33912c2 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -900,6 +900,10 @@ String UseCounter::deprecationMessage(Feature feature)
     case DocumentGetCSSCanvasContext:
         return "The -webkit-canvas CSS feature is deprecated. Please use a positioned <canvas> element instead.";
 
+    case SVGSMILElementInDocument:
+    case SVGSMILAnimationInImageRegardlessOfCache:
+        return "SVG's SMIL animations (<animate>, <set>, etc.) are deprecated and will be removed. Please use CSS animations or Web animations instead.";
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();