Deprecate webkitRequestAnimationFrame and friends as vendor-specific

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 4b25f6d9d5ff05dd05f2230bdeccfb119412fa51..0d83636b3a4750506cb333622fd03282c8171c52 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -685,6 +685,15 @@ String UseCounter::deprecationMessage(Feature feature)
     case PrefixedGamepad:
         return "'navigator.webkitGetGamepads' is deprecated. Please use 'navigator.getGamepads' instead.";
 
+    case PrefixedRequestAnimationFrame:
+        return "'webkitRequestAnimationFrame' is vendor-specific. Please use the standard 'requestAnimationFrame' instead.";
+
+    case PrefixedCancelAnimationFrame:
+        return "'webkitCancelAnimationFrame' is vendor-specific. Please use the standard 'cancelAnimationFrame' instead.";
+
+    case PrefixedCancelRequestAnimationFrame:
+        return "'webkitCancelRequestAnimationFrame' is vendor-specific. Please use the standard 'cancelAnimationFrame' instead.";
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();