Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/webdatabase/SQLTransaction.cpp

 /*
  * Copyright (C) 2007, 2008, 2013 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 156 matching lines @@
         // If we get here with an empty m_transactionError, then the backend
         // must be waiting in the idle state waiting for this state to finish.
         // Hence, it's thread safe to fetch the backend transactionError without
         // a lock.
         if (!m_transactionError)
             m_transactionError = m_backend->transactionError();
 
         ASSERT(m_transactionError);
         errorCallback->handleEvent(m_transactionError.get());
 
-        m_transactionError = 0;
+        m_transactionError = nullptr;
     }
 
     clearCallbackWrappers();
 
     // Spec 4.3.2.10: Rollback the transaction.
     return SQLTransactionState::CleanupAfterTransactionErrorCallback;
 }
 
 SQLTransactionState SQLTransaction::deliverStatementCallback()
 {
@@ skipping 115 matching lines @@
     m_successCallbackWrapper.clear();
     m_errorCallbackWrapper.clear();
 }
 
 PassOwnPtr<SQLTransactionErrorCallback> SQLTransaction::releaseErrorCallback()
 {
     return m_errorCallbackWrapper.unwrap();
 }
 
 } // namespace WebCore