Make createAttributeNS's qualifiedName argument non-nullable

Source/core/dom/Document.idl

Index: Source/core/dom/Document.idl
diff --git a/Source/core/dom/Document.idl b/Source/core/dom/Document.idl
index 5ebbf1193b4b5b5263b07f1695ad3d83ce30db84..a27bc8a8b529bb5d5825558646f1f5656b279ed1 100644
--- a/Source/core/dom/Document.idl
+++ b/Source/core/dom/Document.idl
@@ -61,8 +61,7 @@ interface Document : Node {
     [RaisesException, CustomElementCallbacks, TypeChecking=Interface] Node adoptNode(Node node);
 
     [NewObject, RaisesException, MeasureAs=DocumentCreateAttribute] Attr createAttribute(DOMString localName);
-    // FIXME: qualifiedName should not be nullable.
-    [NewObject, RaisesException, MeasureAs=DocumentCreateAttributeNS] Attr createAttributeNS(DOMString? namespaceURI, DOMString? qualifiedName);
+    [NewObject, RaisesException, MeasureAs=DocumentCreateAttributeNS] Attr createAttributeNS(DOMString? namespaceURI, DOMString qualifiedName);
 
     [NewObject, RaisesException] Event createEvent(DOMString eventType);