Fix release build.

        * bindings/objc/DOM.mm:
        (-[DOMDocument createNodeIterator:whatToShow:filter:expandEntityReferences:]): Add missing null initialization.
        (-[DOMDocument createTreeWalker:whatToShow:filter:expandEntityReferences:]): Add missing null initialization.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@22036 268f45cc-cd09-0410-ab3c-d52691b4dbfc