Return reference from styleEngine() accessor.

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 126 matching lines @@
                 return SelectorFailsLocally;
         } else if (context.selector->isShadowPseudoElement()) {
             if (!context.element->isInShadowTree() || !context.previousElement)
                 return SelectorFailsCompletely;
         } else {
             if ((!context.elementStyle && m_mode == ResolvingStyle) || m_mode == QueryingRules)
                 return SelectorFailsLocally;
 
             PseudoId pseudoId = CSSSelector::pseudoId(context.selector->pseudoType());
             if (pseudoId == FIRST_LETTER)
-                context.element->document().styleEngine()->setUsesFirstLetterRules(true);
+                context.element->document().styleEngine().setUsesFirstLetterRules(true);
             if (pseudoId != NOPSEUDO && m_mode != SharingRules && result)
                 result->dynamicPseudo = pseudoId;
         }
     }
 
     // Prepare next selector
     if (context.selector->isLastInTagHistory()) {
         if (scopeContainsLastMatchedElement(context)) {
             if (result)
                 result->specificity += specificity;
@@ skipping 460 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()))
+                else if (element.layoutStyle() && (element.document().styleEngine().usesSiblingRules() || element.layoutStyle()->unique()))
                     element.layoutStyle()->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();
@@ skipping 547 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;
 
 }