Remove unnecesary usage of RefPtr and PassRefPtr of DatabaseContext.

Source/modules/webdatabase/DatabaseBackend.cpp

 /*
  * 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:
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 22 matching lines @@
 #include "modules/webdatabase/DatabaseTask.h"
 #include "modules/webdatabase/DatabaseThread.h"
 #include "modules/webdatabase/DatabaseTracker.h"
 #include "modules/webdatabase/SQLTransaction.h"
 #include "modules/webdatabase/SQLTransactionBackend.h"
 #include "modules/webdatabase/SQLTransactionClient.h"
 #include "modules/webdatabase/SQLTransactionCoordinator.h"
 
 namespace WebCore {
 
-DatabaseBackend::DatabaseBackend(PassRefPtr<DatabaseContext> databaseContext, const String& name, const String& expectedVersion, const String& displayName, unsigned long estimatedSize)
+DatabaseBackend::DatabaseBackend(DatabaseContext* databaseContext, const String& name, const String& expectedVersion, const String& displayName, unsigned long estimatedSize)
     : DatabaseBackendBase(databaseContext, name, expectedVersion, displayName, estimatedSize, DatabaseType::Async)
     , m_transactionInProgress(false)
     , m_isTransactionQueueEnabled(true)
 {
 }
 
 void DatabaseBackend::trace(Visitor* visitor)
 {
     visitor->trace(m_transactionQueue);
     DatabaseBackendBase::trace(visitor);
@@ skipping 108 matching lines @@
 {
     return databaseContext()->databaseThread()->transactionClient();
 }
 
 SQLTransactionCoordinator* DatabaseBackend::transactionCoordinator() const
 {
     return databaseContext()->databaseThread()->transactionCoordinator();
 }
 
 } // namespace WebCore