Remove Attr child nodes (making Attr a Node, not a ContainerNode)

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 2f464a3333e70606ca2d0a175da2bf5c54f135d2..abc31cf69c2753e1b1891109c9e00cedda221af2 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -877,10 +877,6 @@ String UseCounter::deprecationMessage(Feature feature)
     case ServiceWorkerClientPostMessage:
         return "'Client.postMessage()' is an experimental API and may change. See https://github.com/slightlyoff/ServiceWorker/issues/609.";
 
-    case AttrChildAccess:
-    case AttrChildChange:
-        return "Attr child nodes are deprecated and will be removed in M45, around August 2015. Please use 'Attr.value' 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.";