Move painting code from RenderPart to PartPainter.

Source/core/rendering/RenderPart.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Simon Hausmann <hausmann@kde.org>
  * Copyright (C) 2006, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 35 matching lines @@
 #endif
 
     Widget* widget() const;
 
     void updateOnWidgetChange();
     void updateWidgetPosition();
     void widgetPositionsUpdated();
     bool updateWidgetGeometry();
 
     virtual bool isRenderPart() const override final { return true; }
+    virtual void paintContents(PaintInfo&, const LayoutPoint&);
 
 protected:
     virtual LayerType layerTypeRequired() const override;
 
     virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle) override final;
     virtual void layout() override;
     virtual void paint(PaintInfo&, const LayoutPoint&) override;
-    virtual void paintContents(PaintInfo&, const LayoutPoint&);
     virtual CursorDirective getCursor(const LayoutPoint&, Cursor&) const override final;
 
 private:
     virtual const char* renderName() const override { return "RenderPart"; }
 
     virtual CompositingReasons additionalCompositingReasons() const override;
 
     virtual void willBeDestroyed() override final;
     virtual void destroy() override final;
 
     bool setWidgetGeometry(const LayoutRect&);
 
     bool nodeAtPointOverWidget(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction);
 
 #if !ENABLE(OILPAN)
     int m_refCount;
 #endif
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderPart, isRenderPart());
 
 } // namespace blink
 
 #endif // RenderPart_h