0 -> nullptr for UseCounter pointer in CSSParserContext.

third_party/WebKit/Source/core/html/HTMLContentElement.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 47 matching lines @@
 DEFINE_TRACE(HTMLContentElement)
 {
     visitor->trace(m_filter);
     InsertionPoint::trace(visitor);
 }
 
 void HTMLContentElement::parseSelect()
 {
     ASSERT(m_shouldParseSelect);
 
-    m_selectorList = CSSParser::parseSelector(CSSParserContext(document(), 0), nullptr, m_select);
+    m_selectorList = CSSParser::parseSelector(CSSParserContext(document(), nullptr), nullptr, m_select);
     m_shouldParseSelect = false;
     m_isValidSelector = validateSelect();
     if (!m_isValidSelector)
         m_selectorList = CSSSelectorList();
 }
 
 void HTMLContentElement::parseAttribute(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& value)
 {
     if (name == selectAttr) {
         if (ShadowRoot* root = containingShadowRoot()) {
@@ skipping 48 matching lines @@
     SelectorChecker::SelectorCheckingContext context(&element, SelectorChecker::VisitedMatchDisabled);
     for (const CSSSelector* selector = selectorList().first(); selector; selector = CSSSelectorList::next(*selector)) {
         context.selector = selector;
         if (checker.match(context))
             return true;
     }
     return false;
 }
 
 } // namespace blink