Add an intermediate function to generate 2 paint-order lists.

Source/core/dom/PaintOrderLists.h

+#ifndef PaintOrderLists_h
+#define PaintOrderLists_h
+
+#include "ScriptWrappable.h"
+#include <wtf/RefCounted.h>
+
+namespace WebCore {
+
+class PaintOrderLists : public ScriptWrappable, public RefCounted<PaintOrderLists> {
+public:
+    PaintOrderLists(PassRefPtr<NodeList> listBeforePromote, PassRefPtr<NodeList> listAfterPromote) : m_listBeforePromote(listBeforePromote), m_listAfterPromote(listAfterPromote) { }
+
+    // DOM methods & attributes for NodeList
+    PassRefPtr<NodeList> listBeforePromote() const { return m_listBeforePromote; }
+    PassRefPtr<NodeList> listAfterPromote() const { return m_listAfterPromote; }
+
+    PassRefPtr<NodeList> m_listBeforePromote;
+    PassRefPtr<NodeList> m_listAfterPromote;
+};
+
+} // namespace WebCore
+
+#endif // PaintOrderLists_h