Use nullptr instead of 0 in xml and xmlhttprequest.

Source/core/xml/DocumentXSLT.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/xml/DocumentXSLT.h"
 
 #include "bindings/core/v8/DOMWrapperWorld.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/V8AbstractEventListener.h"
@@ skipping 111 matching lines @@
 ProcessingInstruction* DocumentXSLT::findXSLStyleSheet(Document& document)
 {
     for (Node* node = document.firstChild(); node; node = node->nextSibling()) {
         if (node->nodeType() != Node::PROCESSING_INSTRUCTION_NODE)
             continue;
 
         ProcessingInstruction* pi = toProcessingInstruction(node);
         if (pi->isXSL())
             return pi;
     }
-    return 0;
+    return nullptr;
 }
 
 bool DocumentXSLT::processingInstructionInsertedIntoDocument(Document& document, ProcessingInstruction* pi)
 {
     if (!pi->isXSL())
         return false;
 
     if (!RuntimeEnabledFeatures::xsltEnabled() || !document.frame())
         return true;
 
@@ skipping 53 matching lines @@
     return *supplement;
 }
 
 DEFINE_TRACE(DocumentXSLT)
 {
     visitor->trace(m_transformSourceDocument);
     WillBeHeapSupplement<Document>::trace(visitor);
 }
 
 } // namespace blink