Make RenderObject::style() return a const object

Source/modules/accessibility/AXSlider.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 37 matching lines @@
 {
     return adoptRef(new AXSlider(renderer, axObjectCache));
 }
 
 AccessibilityOrientation AXSlider::orientation() const
 {
     // Default to horizontal in the unknown case.
     if (!m_renderer)
         return AccessibilityOrientationHorizontal;
 
-    RenderStyle* style = m_renderer->style();
+    const RenderStyle* style = m_renderer->style();
     if (!style)
         return AccessibilityOrientationHorizontal;
 
     ControlPart styleAppearance = style->appearance();
     switch (styleAppearance) {
     case SliderThumbHorizontalPart:
     case SliderHorizontalPart:
     case MediaSliderPart:
     case MediaFullScreenVolumeSliderPart:
         return AccessibilityOrientationHorizontal;
@@ skipping 81 matching lines @@
         return LayoutRect();
     return toElement(sliderRenderer->node())->userAgentShadowRoot()->getElementById(ShadowElementNames::sliderThumb())->boundingBox();
 }
 
 bool AXSliderThumb::computeAccessibilityIsIgnored() const
 {
     return accessibilityIsIgnoredByDefault();
 }
 
 } // namespace blink