Make SpeechSynthesis gracefully handle ExecutionContext-less operation.

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 42 matching lines @@
 }
 
 ExecutionContext* SpeechSynthesis::executionContext() const
 {
     return ContextLifecycleObserver::executionContext();
 }
 
 void SpeechSynthesis::voicesDidChange()
 {
     m_voiceList.clear();
-    if (!executionContext()->activeDOMObjectsAreStopped())
+    if (executionContext() && !executionContext()->activeDOMObjectsAreStopped())
         dispatchEvent(Event::create(EventTypeNames::voiceschanged));
 }
 
 const WillBeHeapVector<RefPtrWillBeMember<SpeechSynthesisVoice> >& SpeechSynthesis::getVoices()
 {
     if (m_voiceList.size())
         return m_voiceList;
 
     // If the voiceList is empty, that's the cue to get the voices from the platform again.
     const Vector<RefPtr<PlatformSpeechSynthesisVoice> >& platformVoices = m_platformSpeechSynthesizer->voiceList();
@@ skipping 64 matching lines @@
 
 void SpeechSynthesis::resume()
 {
     if (!currentSpeechUtterance())
         return;
     m_platformSpeechSynthesizer->resume();
 }
 
 void SpeechSynthesis::fireEvent(const AtomicString& type, SpeechSynthesisUtterance* utterance, unsigned long charIndex, const String& name)
 {
-    if (!executionContext()->activeDOMObjectsAreStopped())
+    if (executionContext() && !executionContext()->activeDOMObjectsAreStopped())
         utterance->dispatchEvent(SpeechSynthesisEvent::create(type, charIndex, (currentTime() - utterance->startTime()), name));
 }
 
 void SpeechSynthesis::handleSpeakingCompleted(SpeechSynthesisUtterance* utterance, bool errorOccurred)
 {
     ASSERT(utterance);
 
     // Keep the utterance around long enough to fire an event on it in case m_utteranceQueue
     // is holding the last reference to it.
     RefPtrWillBeRawPtr<SpeechSynthesisUtterance> protect(utterance);
@@ skipping 79 matching lines @@
 }
 
 void SpeechSynthesis::trace(Visitor* visitor)
 {
     visitor->trace(m_voiceList);
     visitor->trace(m_utteranceQueue);
     EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace WebCore