Make RenderObject::style() return a const object

Source/core/paint/BoxPainter.cpp

 // Copyright 2014 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.
 
 #include "config.h"
 #include "core/paint/BoxPainter.h"
 
 #include "core/HTMLNames.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLFrameOwnerElement.h"
@@ skipping 56 matching lines @@
     }
     return bounds;
 }
 
 void BoxPainter::paintBoxDecorationBackgroundWithRect(const PaintInfo& paintInfo, const LayoutPoint& paintOffset, const LayoutRect& paintRect)
 {
     RenderDrawingRecorder recorder(paintInfo.context, m_renderBox, paintInfo.phase, boundsForDrawingRecorder(paintOffset));
     if (recorder.canUseCachedDrawing())
         return;
 
-    RenderStyle* style = m_renderBox.style();
+    const RenderStyle* style = m_renderBox.style();
     BoxDecorationData boxDecorationData(m_renderBox, paintInfo.context);
 
     // FIXME: Should eventually give the theme control over whether the box shadow should paint, since controls could have
     // custom shadows of their own.
     if (!m_renderBox.boxShadowShouldBeAppliedToBackground(boxDecorationData.bleedAvoidance()))
         paintBoxShadow(paintInfo, paintRect, style, Normal);
 
     GraphicsContextStateSaver stateSaver(*paintInfo.context, false);
     if (boxDecorationData.bleedAvoidance() == BackgroundBleedClipBackground) {
         stateSaver.save();
@@ skipping 2096 matching lines @@
 
     FloatPoint secondQuad[4];
     secondQuad[0] = quad[0];
     secondQuad[1] = FloatPoint(quad[0].x() - r1 * cx, quad[0].y() - r1 * cy);
     secondQuad[2] = quad[2];
     secondQuad[3] = quad[3];
     graphicsContext->clipPolygon(4, secondQuad, !secondEdgeMatches);
 }
 
 } // namespace blink