No need to clear the style resolver in Document::childrenChanged

Source/core/dom/Document.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 687 matching lines @@
 {
     if (!frame())
         return 0;
 
     return &domWindow()->location();
 }
 
 void Document::childrenChanged(bool changedByParser, Node* beforeChange, Node* afterChange, int childCountDelta)
 {
     ContainerNode::childrenChanged(changedByParser, beforeChange, afterChange, childCountDelta);
-
-    Element* newDocumentElement = ElementTraversal::firstWithin(*this);
-    if (newDocumentElement == m_documentElement)
-        return;
-    m_documentElement = newDocumentElement;
-    // The root style used for media query matching depends on the document element.
-    clearStyleResolver();
+    m_documentElement = ElementTraversal::firstWithin(*this);
 }
 
 PassRefPtr<Element> Document::createElement(const AtomicString& name, ExceptionState& exceptionState)
 {
     if (!isValidName(name)) {
         exceptionState.throwDOMException(InvalidCharacterError, "The tag name provided ('" + name + "') is not a valid name.");
         return nullptr;
     }
 
     if (isXHTMLDocument() || isHTMLDocument())
@@ skipping 4776 matching lines @@
 }
 
 void Document::invalidateNodeListCaches(const QualifiedName* attrName)
 {
     HashSet<LiveNodeListBase*>::iterator end = m_listsInvalidatedAtDocument.end();
     for (HashSet<LiveNodeListBase*>::iterator it = m_listsInvalidatedAtDocument.begin(); it != end; ++it)
         (*it)->invalidateCache(attrName);
 }
 
 } // namespace WebCore