Deprecate 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 e11986f02a61bb6ac44008fdad447b48abdad5be..12344a890db569fda11cd491fb9fa3dcd441df16 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -866,6 +866,9 @@ 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.";
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();