Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/webdatabase/SQLTransactionCoordinator.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 86 matching lines @@
 
     CoordinationInfoMap::iterator coordinationInfoIterator = m_coordinationInfoMap.find(dbIdentifier);
     ASSERT_WITH_SECURITY_IMPLICATION(coordinationInfoIterator != m_coordinationInfoMap.end());
     CoordinationInfo& info = coordinationInfoIterator->value;
 
     if (transaction->isReadOnly()) {
         ASSERT(info.activeReadTransactions.contains(transaction));
         info.activeReadTransactions.remove(transaction);
     } else {
         ASSERT(info.activeWriteTransaction == transaction);
-        info.activeWriteTransaction = 0;
+        info.activeWriteTransaction = nullptr;
     }
 
     processPendingTransactions(info);
 }
 
 void SQLTransactionCoordinator::shutdown()
 {
     // Prevent releaseLock() from accessing / changing the coordinationInfo
     // while we're shutting down.
     m_isShuttingDown = true;
@@ skipping 22 matching lines @@
             RefPtr<SQLTransactionBackend> transaction = info.pendingTransactions.first();
             transaction->notifyDatabaseThreadIsShuttingDown();
         }
     }
 
     // Clean up all pending transactions for all databases
     m_coordinationInfoMap.clear();
 }
 
 } // namespace WebCore