Add routine for checking startTime when start the next utterance in handleSpeakingCompleted()

Source/modules/speech/SpeechSynthesis.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 150 matching lines @@
         didJustFinishCurrentUtterance = true;
     }
 
     // Always fire the event, because the platform may have asynchronously
     // sent an event on an utterance before it got the message that we
     // canceled it, and we should always report to the user what actually
     // happened.
     fireEvent(errorOccurred ? EventTypeNames::error : EventTypeNames::end, utterance, 0, String());
 
     // Start the next utterance if we just finished one and one was pending.
-    if (didJustFinishCurrentUtterance && !m_utteranceQueue.isEmpty())
+    if (didJustFinishCurrentUtterance && !m_utteranceQueue.isEmpty() && !utterance->startTime())
         startSpeakingImmediately();
 }
 
 void SpeechSynthesis::boundaryEventOccurred(PlatformSpeechSynthesisUtterance* utterance, SpeechBoundary boundary, unsigned charIndex)
 {
     DEFINE_STATIC_LOCAL(const String, wordBoundaryString, ("word"));
     DEFINE_STATIC_LOCAL(const String, sentenceBoundaryString, ("sentence"));
 
     switch (boundary) {
     case SpeechWordBoundary:
@@ skipping 54 matching lines @@
 void SpeechSynthesis::trace(Visitor* visitor)
 {
     visitor->trace(m_platformSpeechSynthesizer);
     visitor->trace(m_voiceList);
     visitor->trace(m_utteranceQueue);
     PlatformSpeechSynthesizerClient::trace(visitor);
     EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace WebCore