0 -> nullptr for UseCounter pointer in CSSParserContext.

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Rob Buis (rwlbuis@gmail.com)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 445 matching lines @@
     // While the stylesheet is asynchronously loading, the owner can be moved under
     // shadow tree.  In that case, cancel any processing on the loaded content.
     if (m_owner->isInShadowTree()) {
         m_loading = false;
         removePendingSheet();
         if (m_sheet)
             clearSheet();
         return;
     }
 
-    CSSParserContext parserContext(m_owner->document(), 0, baseURL, charset);
+    CSSParserContext parserContext(m_owner->document(), nullptr, baseURL, charset);
 
     DEFINE_STATIC_LOCAL(EnumerationHistogram, restoredCachedStyleSheetHistogram, ("Blink.RestoredCachedStyleSheet", 2));
     DEFINE_STATIC_LOCAL(EnumerationHistogram, restoredCachedStyleSheet2Histogram, ("Blink.RestoredCachedStyleSheet2", StyleSheetCacheStatusCount));
 
     if (StyleSheetContents* restoredSheet = const_cast<CSSStyleSheetResource*>(cachedStyleSheet)->restoreParsedStyleSheet(parserContext)) {
         ASSERT(restoredSheet->isCacheableForResource());
         ASSERT(!restoredSheet->isLoading());
 
         if (m_sheet)
             clearSheet();
@@ skipping 241 matching lines @@
 }
 
 DEFINE_TRACE(LinkStyle)
 {
     visitor->trace(m_sheet);
     LinkResource::trace(visitor);
     ResourceOwner<StyleSheetResource>::trace(visitor);
 }
 
 } // namespace blink