Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/loader/EmptyClients.cpp

 /*
  * Copyright (C) 2006 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. 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.
@@ skipping 107 matching lines @@
 {
 }
 
 PassRefPtr<DocumentLoader> EmptyFrameLoaderClient::createDocumentLoader(Frame* frame, const ResourceRequest& request, const SubstituteData& substituteData)
 {
     return DocumentLoader::create(frame, request, substituteData);
 }
 
 PassRefPtr<Frame> EmptyFrameLoaderClient::createFrame(const KURL&, const AtomicString&, const Referrer&, HTMLFrameOwnerElement*)
 {
-    return 0;
+    return nullptr;
 }
 
 PassRefPtr<Widget> EmptyFrameLoaderClient::createPlugin(const IntSize&, HTMLPlugInElement*, const KURL&, const Vector<String>&, const Vector<String>&, const String&, bool)
 {
-    return 0;
+    return nullptr;
 }
 
 PassRefPtr<Widget> EmptyFrameLoaderClient::createJavaAppletWidget(const IntSize&, HTMLAppletElement*, const KURL&, const Vector<String>&, const Vector<String>&)
 {
-    return 0;
+    return nullptr;
 }
 
 void EmptyTextCheckerClient::requestCheckingOfString(PassRefPtr<TextCheckingRequest>)
 {
 }
 
 void EmptyFrameLoaderClient::didRequestAutocomplete(PassRefPtr<FormState>)
 {
 }
 
 PassOwnPtr<blink::WebServiceWorkerProvider> EmptyFrameLoaderClient::createServiceWorkerProvider(PassOwnPtr<blink::WebServiceWorkerProviderClient>)
 {
     return nullptr;
 }
 
 PassOwnPtr<blink::WebApplicationCacheHost> EmptyFrameLoaderClient::createApplicationCacheHost(blink::WebApplicationCacheHostClient*)
 {
     return nullptr;
 }
 
 PassOwnPtr<StorageNamespace> EmptyStorageClient::createSessionStorageNamespace()
 {
     return nullptr;
 }
 
 }