Implement clip and scroll DisplayItems for PartPainter

Source/core/paint/ContentBoxRadiusClipper.h

+// Copyright 2015 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 ContentBoxRadiusClipper_h
+#define ContentBoxRadiusClipper_h
+
+#include "core/rendering/PaintPhase.h"
+#include "platform/geometry/LayoutPoint.h"
+
+namespace blink {
+
+class RenderBox;
+struct PaintInfo;
+
+class ContentBoxRadiusClipper {
+public:
+    ContentBoxRadiusClipper(RenderBox&, const PaintInfo&, const LayoutPoint& accumulatedOffset);
+    ~ContentBoxRadiusClipper();
+    bool completelyClipped() { return m_completelyClipped; }
+
+private:
+    RenderBox& m_box;
+    const PaintInfo& m_paintInfo;
+    bool m_pushedClip;
+    bool m_completelyClipped;
+};
+
+} // namespace blink
+
+#endif // ContentBoxRadiusClipper_h