Extend PlatformSpeechSynthesizerMock with an utterance queue.

Source/modules/speech/SpeechRecognitionResult.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 {
 
 SpeechRecognitionResult* SpeechRecognitionResult::create(const HeapVector<Member<SpeechRecognitionAlternative>>& alternatives, bool final)
 {
     return new SpeechRecognitionResult(alternatives, final);
 }
 
 SpeechRecognitionAlternative* SpeechRecognitionResult::item(unsigned index)
 {
     if (index >= m_alternatives.size())
-        return 0;
+        return nullptr;
 
-    return m_alternatives[index].get();
+    return m_alternatives[index];
 }
 
 SpeechRecognitionResult::SpeechRecognitionResult(const HeapVector<Member<SpeechRecognitionAlternative>>& alternatives, bool final)
     : m_final(final)
     , m_alternatives(alternatives)
 {
 }
 
 void SpeechRecognitionResult::trace(Visitor* visitor)
 {
     visitor->trace(m_alternatives);
 }
 
 } // namespace blink