Make RenderObject::style() return a const object

Source/core/paint/ObjectPainter.cpp

Index: Source/core/paint/ObjectPainter.cpp
diff --git a/Source/core/paint/ObjectPainter.cpp b/Source/core/paint/ObjectPainter.cpp
index 9cebbde0f8ddf8b675ec195c405d5283bc9b04bf..69744cab22caa9dd9a272f8a6724a9b42bc9925f 100644
--- a/Source/core/paint/ObjectPainter.cpp
+++ b/Source/core/paint/ObjectPainter.cpp
@@ -15,7 +15,7 @@
 
 namespace blink {
 
-void ObjectPainter::paintFocusRing(const PaintInfo& paintInfo, const LayoutPoint& paintOffset, RenderStyle* style)
+void ObjectPainter::paintFocusRing(const PaintInfo& paintInfo, const LayoutPoint& paintOffset, const RenderStyle* style)
 {
     Vector<LayoutRect> focusRingRects;
     m_renderObject.addFocusRingRects(focusRingRects, paintOffset);
@@ -28,7 +28,7 @@ void ObjectPainter::paintFocusRing(const PaintInfo& paintInfo, const LayoutPoint
 
 void ObjectPainter::paintOutline(const PaintInfo& paintInfo, const LayoutRect& paintRect)
 {
-    RenderStyle* styleToUse = m_renderObject.style();
+    const RenderStyle* styleToUse = m_renderObject.style();
     if (!styleToUse->hasOutline())
         return;