Return reference from styleEngine() accessor.

Source/core/dom/Document.h

 /*
  * 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) 2011 Google Inc. All rights reserved.
  *
@@ skipping 403 matching lines @@
     void setIsViewSource(bool);
 
     bool sawElementsInKnownNamespaces() const { return m_sawElementsInKnownNamespaces; }
 
     bool isRenderingReady() const { return haveImportsLoaded() && haveStylesheetsLoaded(); }
     bool isScriptExecutionReady() const { return isRenderingReady(); }
 
     // This is a DOM function.
     StyleSheetList* styleSheets();
 
-    StyleEngine* styleEngine() { return m_styleEngine.get(); }
+    StyleEngine& styleEngine() { ASSERT(m_styleEngine.get()); return *m_styleEngine.get(); }
 
     bool gotoAnchorNeededAfterStylesheetsLoad() { return m_gotoAnchorNeededAfterStylesheetsLoad; }
     void setGotoAnchorNeededAfterStylesheetsLoad(bool b) { m_gotoAnchorNeededAfterStylesheetsLoad = b; }
 
     // Called when one or more stylesheets in the document may have been added, removed, or changed.
     void styleResolverChanged(StyleResolverUpdateMode = FullStyleUpdate);
     void styleResolverMayHaveChanged();
 
     // FIXME: Switch all callers of styleResolverChanged to these or better ones and then make them
     // do something smarter.
@@ skipping 548 matching lines @@
     void incrementActiveParserCount() { ++m_activeParserCount; }
     void decrementActiveParserCount() { --m_activeParserCount; }
 
     void setContextFeatures(ContextFeatures&);
     ContextFeatures& contextFeatures() const { return *m_contextFeatures; }
 
     ElementDataCache* elementDataCache() { return m_elementDataCache.get(); }
 
     void didLoadAllScriptBlockingResources();
     void didRemoveAllPendingStylesheet();
-    void clearStyleResolver();
 
     bool inStyleRecalc() const { return m_lifecycle.state() == DocumentLifecycle::InStyleRecalc; }
 
     // Return a Locale for the default locale if the argument is null or empty.
     Locale& getCachedLocale(const AtomicString& locale = nullAtom);
 
     AnimationClock& animationClock() { return m_animationClock; }
     AnimationTimeline& timeline() const { return *m_timeline; }
     CompositorPendingAnimations& compositorPendingAnimations() { return m_compositorPendingAnimations; }
 
@@ skipping 428 matching lines @@
 DEFINE_TYPE_CASTS(TreeScope, Document, document, true, true);
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLiveDocumentInstances();
 #endif
 
 #endif // Document_h