Make RenderObject::style() return a const object

Source/core/css/SelectorChecker.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 607 matching lines @@
                     if (!textNode->data().isEmpty()) {
                         result = false;
                         break;
                     }
                 }
             }
             if (m_mode == ResolvingStyle) {
                 element.setStyleAffectedByEmpty();
                 if (context.elementStyle)
                     context.elementStyle->setEmptyState(result);
-                else if (element.layoutStyle() && (element.document().styleEngine()->usesSiblingRules() || element.layoutStyle()->unique()))
-                    element.layoutStyle()->setEmptyState(result);
+                else if (element.mutableLayoutStyle() && (element.document().styleEngine()->usesSiblingRules() || element.mutableLayoutStyle()->unique()))
+                    element.mutableLayoutStyle()->setEmptyState(result);
             }
             return result;
         }
     case CSSSelector::PseudoFirstChild:
         // first-child matches the first child that is an element
         if (ContainerNode* parent = element.parentElementOrDocumentFragment()) {
             bool result = siblingTraversalStrategy.isFirstChild(element);
             if (m_mode == ResolvingStyle) {
                 parent->setChildrenAffectedByFirstChildRules();
                 element.setAffectedByFirstChildRules();
@@ skipping 55 matching lines @@
                 return false;
             return siblingTraversalStrategy.isFirstOfType(element, element.tagQName()) && siblingTraversalStrategy.isLastOfType(element, element.tagQName());
         }
         break;
     case CSSSelector::PseudoNthChild:
         if (!selector.parseNth())
             break;
         if (ContainerNode* parent = element.parentElementOrDocumentFragment()) {
             int count = 1 + siblingTraversalStrategy.countElementsBefore(element);
             if (m_mode == ResolvingStyle) {
-                LayoutStyle* childStyle = context.elementStyle ? context.elementStyle : element.layoutStyle();
+                const LayoutStyle* childStyle = context.elementStyle ? context.elementStyle : element.layoutStyle();
                 if (childStyle)
                     childStyle->setUnique();
                 parent->setChildrenAffectedByForwardPositionalRules();
             }
 
             if (selector.matchNth(count))
                 return true;
         }
         break;
     case CSSSelector::PseudoNthOfType:
@@ skipping 470 matching lines @@
     return isHTMLSelectElement(element) && !toHTMLSelectElement(element).usesMenuList();
 }
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const DOMSiblingTraversalStrategy&, MatchResult*) const;
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const ShadowDOMSiblingTraversalStrategy&, MatchResult*) const;
 
 }