Use IDL argument default values in modules/indexeddb/

Source/modules/indexeddb/IDBTransaction.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:
  *
  * 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 283 matching lines @@
 bool IDBTransaction::hasPendingActivity() const
 {
     // FIXME: In an ideal world, we should return true as long as anyone has a or can
     //        get a handle to us or any child request object and any of those have
     //        event listeners. This is  in order to handle user generated events properly.
     return m_hasPendingActivity && !m_contextStopped;
 }
 
 blink::WebIDBTransactionMode IDBTransaction::stringToMode(const String& modeString, ExceptionState& exceptionState)
 {
-    if (modeString.isNull()
-        || modeString == IDBTransaction::modeReadOnly())
+    if (modeString == IDBTransaction::modeReadOnly())
         return blink::WebIDBTransactionModeReadOnly;
     if (modeString == IDBTransaction::modeReadWrite())
         return blink::WebIDBTransactionModeReadWrite;
 
     exceptionState.throwTypeError("The mode provided ('" + modeString + "') is not one of 'readonly' or 'readwrite'.");
     return blink::WebIDBTransactionModeReadOnly;
 }
 
 const AtomicString& IDBTransaction::modeToString(blink::WebIDBTransactionMode mode)
 {
@@ skipping 83 matching lines @@
     event->setTarget(this);
     eventQueue->enqueueEvent(event);
 }
 
 blink::WebIDBDatabase* IDBTransaction::backendDB() const
 {
     return m_database->backend();
 }
 
 } // namespace WebCore