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

If you delete the documentElement then that also means all <style> and
<link> elements must have been removed from the document so the
StyleResolver should already be reset or cleared and we don't need to
call clearStyleResolver() from inside Document::childrenChanged.

Review URL: https://codereview.chromium.org/209383015

git-svn-id: svn://svn.chromium.org/blink/trunk@169911 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/dom/Document.cpp

@@ -705,13 +705,7 @@ Location* Document::location() const
 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)