Use nullptr instead of 0 in xml and xmlhttprequest.

Source/core/xml/XPathFunctions.cpp

 /*
  * Copyright (C) 2005 Frerich Raabe <raabe@kde.org>
  * Copyright (C) 2006, 2009 Apple 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 578 matching lines @@
 
 Value FunTrue::evaluate(EvaluationContext&) const
 {
     return true;
 }
 
 Value FunLang::evaluate(EvaluationContext& context) const
 {
     String lang = arg(0)->evaluate(context).toString();
 
-    const Attribute* languageAttribute = 0;
+    const Attribute* languageAttribute = nullptr;
     Node* node = context.node.get();
     while (node) {
         if (node->isElementNode()) {
             Element* element = toElement(node);
             languageAttribute = element->attributes().find(XMLNames::langAttr);
         }
         if (languageAttribute)
             break;
         node = node->parentNode();
     }
@@ skipping 119 matching lines @@
     HeapVector<Member<Expression>> args;
     return createFunction(name, args);
 }
 
 Function* createFunction(const String& name, HeapVector<Member<Expression>>& args)
 {
     if (!functionMap)
         createFunctionMap();
 
     HashMap<String, FunctionRec>::iterator functionMapIter = functionMap->find(name);
-    FunctionRec* functionRec = 0;
+    FunctionRec* functionRec = nullptr;
 
     if (functionMapIter == functionMap->end() || !(functionRec = &functionMapIter->value)->args.contains(args.size()))
-        return 0;
+        return nullptr;
 
     Function* function = functionRec->factoryFn();
     function->setArguments(args);
     function->setName(name);
     return function;
 }
 
 }
 }