Remove unnecesary usage of RefPtr and PassRefPtr of DatabaseContext.

Source/modules/webdatabase/DatabaseContext.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2011 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:
  * 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 126 matching lines @@
 }
 
 // stop() is from stopActiveDOMObjects() which indicates that the owner LocalFrame
 // or WorkerThread is shutting down. Initiate the orderly shutdown by stopping
 // the associated databases.
 void DatabaseContext::stop()
 {
     stopDatabases();
 }
 
-PassRefPtr<DatabaseContext> DatabaseContext::backend()
+DatabaseContext* DatabaseContext::backend()
 {
-    DatabaseContext* backend = static_cast<DatabaseContext*>(this);
-    return backend;
+    return this;
 }
 
 DatabaseThread* DatabaseContext::databaseThread()
 {
     if (!m_databaseThread && !m_hasOpenDatabases) {
         // It's OK to ask for the m_databaseThread after we've requested
         // termination because we're still using it to execute the closing
         // of the database. However, it is NOT OK to create a new thread
         // after we've requested termination.
         ASSERT(!m_hasRequestedTermination);
@@ skipping 79 matching lines @@
 {
     return executionContext()->securityOrigin();
 }
 
 bool DatabaseContext::isContextThread() const
 {
     return executionContext()->isContextThread();
 }
 
 } // namespace WebCore