Remove [TreatNullAs=NullString] from Document.cookie

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..f18f804d8609a197b9d79b1e6974e99ad8fc9212 100644
--- a/Source/core/dom/Document.idl
+++ b/Source/core/dom/Document.idl
@@ -87,8 +87,7 @@ interface Document : Node {
     [PutForwards=href, Unforgeable] readonly attribute Location? location;
     [RaisesException=Setter] attribute DOMString domain;
     readonly attribute DOMString referrer;
-    // FIXME: cookie should not have [TreatNullAs=NullString].
-    [TreatNullAs=NullString, RaisesException] attribute DOMString cookie;
+    [RaisesException] attribute DOMString cookie;
     readonly attribute DOMString lastModified;
     readonly attribute DocumentReadyState readyState;