Allow <link rel=stylesheet> in a connected shadow tree

third_party/WebKit/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 173 matching lines @@
     }
 
     resolverChanged(updateMode);
 }
 
 void StyleEngine::addStyleSheetCandidateNode(Node* node)
 {
     if (!node->isConnected() || document().isDetached())
         return;
 
-    TreeScope& treeScope = isStyleElement(*node) ? node->treeScope() : *m_document;
     DCHECK(!isXSLStyleSheet(*node));
+    TreeScope& treeScope = node->treeScope();
     TreeScopeStyleSheetCollection* collection = ensureStyleSheetCollectionFor(treeScope);
     DCHECK(collection);
     collection->addStyleSheetCandidateNode(node);
 
     markTreeScopeDirty(treeScope);
     if (treeScope != m_document)
         m_activeTreeScopes.add(&treeScope);
 }
 
 void StyleEngine::removeStyleSheetCandidateNode(Node* node)
@@ skipping 623 matching lines @@
 
 DEFINE_TRACE_WRAPPERS(StyleEngine)
 {
     for (auto sheet : m_injectedAuthorStyleSheets) {
         visitor->traceWrappers(sheet);
     }
     visitor->traceWrappers(m_documentStyleSheetCollection);
 }
 
 } // namespace blink