Deprecate Attr child nodes

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 03fb99a6ddae12ed3ebf27b9de73dfba2ee94ce5..e11986f02a61bb6ac44008fdad447b48abdad5be 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -862,6 +862,10 @@ String UseCounter::deprecationMessage(Feature feature)
     case ServiceWorkerClientsGetAll:
         return "'Clients.getAll()' is deprecated and will be removed soon. Please use 'Clients.matchAll()' instead.";
 
+    case AttrChildAccess:
+    case AttrChildChange:
+        return "Attr child nodes are deprecated and will be removed in M45, around August 2015. Please use 'Attr.value' instead.";
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();