Extend PlatformSpeechSynthesizerMock with an utterance queue.

Source/modules/speech/SpeechRecognitionResultList.cpp

 /*
  * Copyright (C) 2012 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:
  *  * Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *  * Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 19 matching lines @@
 namespace blink {
 
 SpeechRecognitionResultList* SpeechRecognitionResultList::create(const HeapVector<Member<SpeechRecognitionResult>>& results)
 {
     return new SpeechRecognitionResultList(results);
 }
 
 SpeechRecognitionResult* SpeechRecognitionResultList::item(unsigned index)
 {
     if (index >= m_results.size())
-        return 0;
+        return nullptr;
 
-    return m_results[index].get();
+    return m_results[index];
 }
 
 SpeechRecognitionResultList::SpeechRecognitionResultList(const HeapVector<Member<SpeechRecognitionResult>>& results)
     : m_results(results)
 {
 }
 
 void SpeechRecognitionResultList::trace(Visitor* visitor)
 {
     visitor->trace(m_results);
 }
 
 } // namespace blink