Return reference from styleEngine() accessor.

Source/core/dom/ShadowTreeStyleSheetCollection.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
@@ skipping 27 matching lines @@
 
 namespace blink {
 
 using namespace HTMLNames;
 
 ShadowTreeStyleSheetCollection::ShadowTreeStyleSheetCollection(ShadowRoot& shadowRoot)
     : TreeScopeStyleSheetCollection(shadowRoot)
 {
 }
 
-void ShadowTreeStyleSheetCollection::collectStyleSheets(StyleEngine* engine, StyleSheetCollection& collection)
+void ShadowTreeStyleSheetCollection::collectStyleSheets(StyleEngine& engine, StyleSheetCollection& collection)
 {
     for (Node* n : m_styleSheetCandidateNodes) {
         StyleSheetCandidate candidate(*n);
         ASSERT(!candidate.isXSL());
 
         if (!candidate.isCSSStyle())
             continue;
 
         StyleSheet* sheet = candidate.sheet();
         if (!sheet)
             continue;
 
         // FIXME: clarify how PREFERRED or ALTERNATE works in shadow trees.
         // Should we set preferred/selected stylesheets name in shadow trees and
         // use the name in document?
-        if (candidate.hasPreferrableName(engine->preferredStylesheetSetName()))
-            engine->selectStylesheetSetName(candidate.title());
+        if (candidate.hasPreferrableName(engine.preferredStylesheetSetName()))
+            engine.selectStylesheetSetName(candidate.title());
 
         collection.appendSheetForList(sheet);
-        if (candidate.canBeActivated(engine->preferredStylesheetSetName()))
+        if (candidate.canBeActivated(engine.preferredStylesheetSetName()))
             collection.appendActiveStyleSheet(toCSSStyleSheet(sheet));
     }
 }
 
-void ShadowTreeStyleSheetCollection::updateActiveStyleSheets(StyleEngine* engine, StyleResolverUpdateMode updateMode)
+void ShadowTreeStyleSheetCollection::updateActiveStyleSheets(StyleEngine& engine, StyleResolverUpdateMode updateMode)
 {
     StyleSheetCollection collection;
     collectStyleSheets(engine, collection);
 
     StyleSheetChange change;
     analyzeStyleSheetChange(updateMode, collection, change);
 
-    if (StyleResolver* styleResolver = engine->resolver()) {
+    if (StyleResolver* styleResolver = engine.resolver()) {
         if (change.styleResolverUpdateType != Additive) {
             // We should not destroy StyleResolver when we find any stylesheet update in a shadow tree.
             // In this case, we will reset rulesets created from style elements in the shadow tree.
             styleResolver->resetAuthorStyle(treeScope());
             styleResolver->removePendingAuthorStyleSheets(m_activeAuthorStyleSheets);
             styleResolver->lazyAppendAuthorStyleSheets(0, collection.activeAuthorStyleSheets());
         } else {
             styleResolver->lazyAppendAuthorStyleSheets(m_activeAuthorStyleSheets.size(), collection.activeAuthorStyleSheets());
         }
     }
     if (change.requiresFullStyleRecalc)
         toShadowRoot(treeScope().rootNode()).host()->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::ActiveStylesheetsUpdate));
 
     collection.swap(*this);
     updateUsesRemUnits();
 }
 
 }