Factor painting code out of RenderBox into a new class called BoxPainter.

Source/core/rendering/RenderFieldset.cpp

Index: Source/core/rendering/RenderFieldset.cpp
diff --git a/Source/core/rendering/RenderFieldset.cpp b/Source/core/rendering/RenderFieldset.cpp
index 928eb192be8a5adb3b1f07c6af901dfe20bf9d74..956c95351ac20ef689d2341f55224b5215548bf3 100644
--- a/Source/core/rendering/RenderFieldset.cpp
+++ b/Source/core/rendering/RenderFieldset.cpp
@@ -27,6 +27,7 @@
 #include "core/CSSPropertyNames.h"
 #include "core/HTMLNames.h"
 #include "core/html/HTMLLegendElement.h"
+#include "core/rendering/BoxDecorationData.h"
 #include "core/rendering/PaintInfo.h"
 #include "platform/graphics/GraphicsContextStateSaver.h"
 
@@ -39,6 +40,7 @@ using namespace HTMLNames;
 
 RenderFieldset::RenderFieldset(Element* element)
     : RenderBlockFlow(element)
+    , m_boxPainter(BoxPainter(*this))
 {
 }
 
@@ -159,11 +161,11 @@ void RenderFieldset::paintBoxDecorationBackground(PaintInfo& paintInfo, const La
         paintRect.setX(paintRect.x() + xOff);
     }
 
-    BoxDecorationData boxDecorationData(*style());
+    BoxDecorationData boxDecorationData(*style(), canRenderBorderImage(), backgroundHasOpaqueTopLayer(), paintInfo.context);
 
-    if (!boxShadowShouldBeAppliedToBackground(determineBackgroundBleedAvoidance(paintInfo.context, boxDecorationData)))
+    if (boxDecorationData.bleedAvoidance == BackgroundBleedNone)
         paintBoxShadow(paintInfo, paintRect, style(), Normal);
-    paintFillLayers(paintInfo, boxDecorationData.backgroundColor, style()->backgroundLayers(), paintRect);
+    m_boxPainter.paintFillLayers(paintInfo, boxDecorationData.backgroundColor, style()->backgroundLayers(), paintRect);
     paintBoxShadow(paintInfo, paintRect, style(), Inset);
 
     if (!boxDecorationData.hasBorder)
@@ -212,7 +214,7 @@ void RenderFieldset::paintMask(PaintInfo& paintInfo, const LayoutPoint& paintOff
         paintRect.move(xOff, 0);
     }
 
-    paintMaskImages(paintInfo, paintRect);
+    m_boxPainter.paintMaskImages(paintInfo, paintRect);
 }
 
 } // namespace blink