Remove CSSKeyframesRule.insertRule()

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 3c734e64fe73e7d161c08694e6bd2915f5e1aa52..33bafef013b2aea137be946057d0acf01259e2fc 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -881,9 +881,6 @@ String UseCounter::deprecationMessage(Feature feature)
     case AttrChildChange:
         return "Attr child nodes are deprecated and will be removed in M45, around August 2015. Please use 'Attr.value' instead.";
 
-    case CSSKeyframesRuleInsertRule:
-        return "'CSSKeyframesRule.insertRule()' is deprecated and will be removed in M45, around August 2015. Please use 'CSSKeyframesRule.appendRule()' instead.";
-
     // Powerful features on insecure origins (https://goo.gl/rStTGz)
     case GeolocationInsecureOrigin:
         return "getCurrentPosition() and watchPosition() are deprecated on insecure origins, and support will be removed in the future. You should consider switching your application to a secure origin, such as HTTPS. See https://goo.gl/rStTGz for more details.";