Move paint code from RenderMultiColumnSet to MultiColumnSetPainter.

Source/core/paint/MultiColumnSetPainter.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MultiColumnSetPainter_h
+#define MultiColumnSetPainter_h
+
+namespace blink {
+
+struct PaintInfo;
+class LayoutPoint;
+class RenderMultiColumnSet;
+
+class MultiColumnSetPainter {
+public:
+    MultiColumnSetPainter(RenderMultiColumnSet& renderMultiColumnSet) : m_renderMultiColumnSet(renderMultiColumnSet) { }
+    void paintObject(PaintInfo&, const LayoutPoint& paintOffset);
+
+private:
+    void paintColumnRules(PaintInfo&, const LayoutPoint& paintOffset);
+
+    RenderMultiColumnSet& m_renderMultiColumnSet;
+};
+
+} // namespace blink
+
+#endif // MultiColumnSetPainter_h