Make RenderObject::style() return a const object

Source/core/rendering/RenderCombineText.cpp

 /*
  * Copyright (C) 2011 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 98 matching lines @@
     FontDescription description = originalFont().fontDescription();
     float emWidth = description.computedSize();
     if (!(style()->textDecorationsInEffect() & (TextDecorationUnderline | TextDecorationOverline)))
         emWidth *= textCombineMargin;
 
     description.setOrientation(Horizontal); // We are going to draw combined text horizontally.
     m_combinedTextWidth = originalFont().width(run);
 
     FontSelector* fontSelector = style()->font().fontSelector();
 
-    bool shouldUpdateFont = style()->setFontDescription(description); // Need to change font orientation to horizontal.
+    bool shouldUpdateFont = mutableStyleRef().setFontDescription(description); // Need to change font orientation to horizontal.
 
     if (m_combinedTextWidth <= emWidth) {
         m_scaleX = 1.0f;
     } else {
         // Need to try compressed glyphs.
         static const FontWidthVariant widthVariants[] = { HalfWidth, ThirdWidth, QuarterWidth };
         for (size_t i = 0 ; i < WTF_ARRAY_LENGTH(widthVariants) ; ++i) {
             description.setWidthVariant(widthVariants[i]);
             Font compressedFont = Font(description);
             compressedFont.update(fontSelector);
             float runWidth = compressedFont.width(run);
             if (runWidth <= emWidth) {
                 m_combinedTextWidth = runWidth;
 
                 // Replace my font with the new one.
-                shouldUpdateFont = style()->setFontDescription(description);
+                shouldUpdateFont = mutableStyleRef().setFontDescription(description);
                 break;
             }
         }
 
         // If width > ~1em, shrink to fit within ~1em, otherwise render without scaling (no expansion)
         // http://dev.w3.org/csswg/css-writing-modes-3/#text-combine-compression
         if (m_combinedTextWidth > emWidth) {
             m_scaleX = emWidth / m_combinedTextWidth;
             m_combinedTextWidth = emWidth;
         } else {
             m_scaleX = 1.0f;
         }
     }
 
     if (shouldUpdateFont)
         style()->font().update(fontSelector);
 }
 
 } // namespace blink