Make RenderObject::style() return a const object

Source/core/layout/LayoutThemeChromiumDefault.cpp

 /*
  * Copyright (C) 2007 Apple Inc.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Collabora Ltd.
  * Copyright (C) 2008, 2009 Google Inc.
  * Copyright (C) 2009 Kenneth Rohde Christiansen
  *
  * 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
@@ skipping 472 matching lines @@
     WebCanvas* canvas = i.context->canvas();
     Platform::current()->themeEngine()->paint(canvas, WebThemeEngine::PartProgressBar, getWebThemeState(this, o), WebRect(rect), &extraParams);
     return false;
 }
 
 bool LayoutThemeChromiumDefault::shouldOpenPickerWithF4Key() const
 {
     return true;
 }
 
-bool LayoutThemeChromiumDefault::shouldUseFallbackTheme(RenderStyle* style) const
+bool LayoutThemeChromiumDefault::shouldUseFallbackTheme(const RenderStyle* style) const
 {
     if (useMockTheme()) {
         // The mock theme can't handle zoomed controls, so we fall back to the "fallback" theme.
         ControlPart part = style->appearance();
         if (part == CheckboxPart || part == RadioPart)
             return style->effectiveZoom() != 1;
     }
     return LayoutTheme::shouldUseFallbackTheme(style);
 }
 
 } // namespace blink