Use nullptr instead of 0 in xml and xmlhttprequest.

Source/core/xml/XPathParser.cpp

 /*
  * Copyright 2005 Maksim Orlovich <maksim@kde.org>
  * Copyright (C) 2006 Apple Computer, Inc.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  *
  * 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
@@ skipping 24 matching lines @@
 #include "core/xml/XPathNSResolver.h"
 #include "core/xml/XPathPath.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/text/StringHash.h"
 
 using namespace blink;
 using namespace WTF;
 using namespace Unicode;
 using namespace XPath;
 
-Parser* Parser::currentParser = 0;
+Parser* Parser::currentParser = nullptr;
 
 enum XMLCat { NameStart, NameCont, NotPartOfName };
 
 typedef HashMap<String, Step::Axis> AxisNamesMap;
 
 static XMLCat charCat(UChar aChar)
 {
     // might need to add some special cases from the XML spec.
 
     if (aChar == '_')
@@ skipping 450 matching lines @@
 
 void Parser::deleteString(String* s)
 {
     if (s == 0)
         return;
 
     ASSERT(m_strings.contains(s));
 
     m_strings.remove(s);
 }