--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/JavaScriptCore/runtime/StringObjectThatMasqueradesAsUndefined.h	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,57 @@
+/*
+ *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
+ *  Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifndef StringObjectThatMasqueradesAsUndefined_h
+#define StringObjectThatMasqueradesAsUndefined_h
+
+#include "JSGlobalObject.h"
+#include "StringObject.h"
+#include "UString.h"
+
+namespace JSC {
+
+    // WebCore uses this to make style.filter undetectable
+    class StringObjectThatMasqueradesAsUndefined : public StringObject {
+    public:
+        static StringObjectThatMasqueradesAsUndefined* create(ExecState* exec, const UString& string)
+        {
+            return new (exec) StringObjectThatMasqueradesAsUndefined(exec,
+                createStructure(exec->lexicalGlobalObject()->stringPrototype()), string);
+        }
+
+    private:
+        StringObjectThatMasqueradesAsUndefined(ExecState* exec, NonNullPassRefPtr<Structure> structure, const UString& string)
+            : StringObject(exec, structure, string)
+        {
+        }
+
+        static PassRefPtr<Structure> createStructure(JSValue proto) 
+        { 
+            return Structure::create(proto, TypeInfo(ObjectType, StructureFlags), AnonymousSlotCount); 
+        }
+
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | MasqueradesAsUndefined | OverridesGetPropertyNames | StringObject::StructureFlags;
+
+        virtual bool toBoolean(ExecState*) const { return false; }
+    };
+ 
+} // namespace JSC
+
+#endif // StringObjectThatMasqueradesAsUndefined_h