We should unify various forms of tree traversal in DOM

Source/core/dom/StyleEngine.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, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 20 matching lines @@
 #include "HTMLNames.h"
 #include "SVGNames.h"
 #include "core/css/CSSFontSelector.h"
 #include "core/css/CSSStyleSheet.h"
 #include "core/css/StyleInvalidationAnalysis.h"
 #include "core/css/StyleSheetContents.h"
 #include "core/dom/Element.h"
 #include "core/dom/ProcessingInstruction.h"
 #include "core/dom/ShadowTreeStyleSheetCollection.h"
 #include "core/dom/shadow/ShadowRoot.h"
+#include "core/frame/Settings.h"
 #include "core/html/HTMLIFrameElement.h"
 #include "core/html/HTMLImport.h"
 #include "core/html/HTMLLinkElement.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/page/Page.h"
 #include "core/page/PageGroup.h"
-#include "core/frame/Settings.h"
 #include "core/svg/SVGStyleElement.h"
 #include "platform/URLPatternMatcher.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
 StyleEngine::StyleEngine(Document& document)
     : m_document(document)
     , m_isMaster(HTMLImport::isMaster(&document))
@@ skipping 288 matching lines @@
     m_documentStyleSheetCollection.clearMediaQueryRuleSetStyleSheets();
     clearMediaQueryRuleSetOnTreeScopeStyleSheets(m_activeTreeScopes);
     clearMediaQueryRuleSetOnTreeScopeStyleSheets(m_dirtyTreeScopes);
 }
 
 void StyleEngine::collectDocumentActiveStyleSheets(StyleSheetCollectionBase& collection)
 {
     ASSERT(isMaster());
 
     if (HTMLImport* rootImport = m_document.import()) {
-        for (HTMLImport* import = traverseFirstPostOrder(rootImport); import; import = traverseNextPostOrder(import)) {
+        for (HTMLImport* import = traverseFirstPostOrder(*rootImport); import; import = traverseNextPostOrder(*import)) {
             Document* document = import->document();
             if (!document)
                 continue;
             StyleEngine* engine = document->styleEngine();
             DocumentStyleSheetCollection::CollectFor collectFor = document == &m_document ?
                 DocumentStyleSheetCollection::CollectForList : DocumentStyleSheetCollection::DontCollectForList;
             engine->m_documentStyleSheetCollection.collectStyleSheets(engine, collection, collectFor);
         }
     } else {
         m_documentStyleSheetCollection.collectStyleSheets(this, collection, DocumentStyleSheetCollection::CollectForList);
@@ skipping 214 matching lines @@
 }
 
 void StyleEngine::markDocumentDirty()
 {
     m_documentScopeDirty = true;
     if (!HTMLImport::isMaster(&m_document))
         m_document.import()->master()->styleEngine()->markDocumentDirty();
 }
 
 }