Track reasons for |Node::SetNeedsStyleRecalc|

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 89 matching lines @@
             // 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);
+        toShadowRoot(treeScope().rootNode()).host()->setNeedsStyleRecalc(StyleRecalcDueToActiveStylesheetsUpdate, SubtreeStyleChange);
 
     collection.swap(*this);
     updateUsesRemUnits();
 }
 
 }