0 -> nullptr for UseCounter pointer in CSSParserContext.

third_party/WebKit/Source/core/inspector/InspectorCSSAgent.cpp

 /*
  * Copyright (C) 2010, 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:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 84 matching lines @@
     FrontendOperationScope() { ++s_frontendOperationCounter; }
     ~FrontendOperationScope() { --s_frontendOperationCounter; }
 };
 
 using namespace blink;
 
 String createShorthandValue(Document* document, const String& shorthand, const String& oldText, const String& longhand, const String& newValue)
 {
     StyleSheetContents* styleSheetContents = StyleSheetContents::create(strictCSSParserContext());
     String text = " div { " + shorthand  + ": " + oldText + "; }";
-    CSSParser::parseSheet(CSSParserContext(*document, 0), styleSheetContents, text);
+    CSSParser::parseSheet(CSSParserContext(*document, nullptr), styleSheetContents, text);
 
     CSSStyleSheet* styleSheet = CSSStyleSheet::create(styleSheetContents);
     CSSStyleRule* rule = toCSSStyleRule(styleSheet->item(0));
     CSSStyleDeclaration* style = rule->style();
     TrackExceptionState exceptionState;
     style->setProperty(longhand, newValue, style->getPropertyPriority(longhand), exceptionState);
     return style->getPropertyValue(shorthand);
 }
 
 HeapVector<Member<CSSStyleRule>> filterDuplicateRules(CSSRuleList* ruleList)
@@ skipping 1956 matching lines @@
     visitor->trace(m_cssStyleSheetToInspectorStyleSheet);
     visitor->trace(m_documentToCSSStyleSheets);
     visitor->trace(m_invalidatedDocuments);
     visitor->trace(m_nodeToInspectorStyleSheet);
     visitor->trace(m_documentToViaInspectorStyleSheet);
     visitor->trace(m_inspectorUserAgentStyleSheet);
     InspectorBaseAgent::trace(visitor);
 }
 
 } // namespace blink