Make RenderObject::style() return a const object

Source/core/rendering/RenderBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 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 574 matching lines @@
         if (isHorizontalWritingMode())
             rect.setY(m_frameRect.height() - rect.maxY());
         else
             rect.setX(m_frameRect.width() - rect.maxX());
     }
     // These represent your location relative to your container as a physical offset.
     // In layout related methods you almost always want the logical location (e.g. x() and y()).
     LayoutPoint topLeftLocation() const;
     LayoutSize topLeftLocationOffset() const { return toLayoutSize(topLeftLocation()); }
 
-    LayoutRect logicalVisualOverflowRectForPropagation(RenderStyle*) const;
-    LayoutRect visualOverflowRectForPropagation(RenderStyle*) const;
-    LayoutRect logicalLayoutOverflowRectForPropagation(RenderStyle*) const;
-    LayoutRect layoutOverflowRectForPropagation(RenderStyle*) const;
+    LayoutRect logicalVisualOverflowRectForPropagation(const RenderStyle*) const;
+    LayoutRect visualOverflowRectForPropagation(const RenderStyle*) const;
+    LayoutRect logicalLayoutOverflowRectForPropagation(const RenderStyle*) const;
+    LayoutRect layoutOverflowRectForPropagation(const RenderStyle*) const;
 
     bool hasRenderOverflow() const { return m_overflow; }
     bool hasVisualOverflow() const { return m_overflow && !borderBoxRect().contains(m_overflow->visualOverflowRect()); }
 
     virtual bool needsPreferredWidthsRecalculation() const;
     virtual void computeIntrinsicRatioInformation(FloatSize& /* intrinsicSize */, double& /* intrinsicRatio */) const { }
 
     IntSize scrolledContentOffset() const;
     void applyCachedClipAndScrollOffsetForPaintInvalidation(LayoutRect& paintRect) const;
 
@@ skipping 232 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != 0))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace blink
 
 #endif // RenderBox_h