Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/filesystem/DOMFileSystem.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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 46 matching lines @@
 PassRefPtr<DOMFileSystem> DOMFileSystem::create(ExecutionContext* context, const String& name, FileSystemType type, const KURL& rootURL)
 {
     RefPtr<DOMFileSystem> fileSystem(adoptRef(new DOMFileSystem(context, name, type, rootURL)));
     fileSystem->suspendIfNeeded();
     return fileSystem.release();
 }
 
 PassRefPtr<DOMFileSystem> DOMFileSystem::createIsolatedFileSystem(ExecutionContext* context, const String& filesystemId)
 {
     if (filesystemId.isEmpty())
-        return 0;
+        return nullptr;
 
     StringBuilder filesystemName;
     filesystemName.append(createDatabaseIdentifierFromSecurityOrigin(context->securityOrigin()));
     filesystemName.append(":Isolated_");
     filesystemName.append(filesystemId);
 
     // The rootURL created here is going to be attached to each filesystem request and
     // is to be validated each time the request is being handled.
     StringBuilder rootURL;
     rootURL.append("filesystem:");
@@ skipping 119 matching lines @@
 
 } // namespace
 
 void DOMFileSystem::createFile(const FileEntry* fileEntry, PassOwnPtr<FileCallback> successCallback, PassOwnPtr<ErrorCallback> errorCallback)
 {
     KURL fileSystemURL = createFileSystemURL(fileEntry);
     fileSystem()->createSnapshotFileAndReadMetadata(fileSystemURL, SnapshotFileCallback::create(this, fileEntry->name(), fileSystemURL, successCallback, errorCallback));
 }
 
 } // namespace WebCore