Revert regression in AudioBufferSourceNode.start() with no buffer

Source/modules/webaudio/AudioScheduledSourceNode.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:
  * 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 118 matching lines @@
             for (unsigned i = 0; i < outputBus->numberOfChannels(); ++i)
                 memset(outputBus->channel(i)->mutableData() + zeroStartFrame, 0, sizeof(float) * framesToZero);
         }
 
         finish();
     }
 
     return;
 }
 
-
 void AudioScheduledSourceNode::start(double when, ExceptionState& exceptionState)
 {
     ASSERT(isMainThread());
 
     if (m_playbackState != UNSCHEDULED_STATE) {
         exceptionState.throwDOMException(
             InvalidStateError,
             "cannot call start more than once.");
         return;
     }
@@ skipping 56 matching lines @@
 void AudioScheduledSourceNode::NotifyEndedTask::notifyEnded()
 {
     RefPtr<Event> event = Event::create(EventTypeNames::ended);
     event->setTarget(m_scheduledNode);
     m_scheduledNode->dispatchEvent(event.get());
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)