anchor.diff:  
     double get volume => _gain.gain.value;
   
  +  static bool _webAudioSupport = null;
  +  /**
  +   * Whether or not the browser supports WebAudio. Applications should
  +   * gracefully handle a lack of WebAudio support by not playing
  +   * audio, instead of simply crashing. However, it is likely
  +   * that any browser supporting WebGL also supports WebAudio.
  +   */
  +  static bool get webAudioSupport {
  +    if (_webAudioSupport == null) {
  +      var jswindow = new JsObject.fromBrowserObject(window);
  +      _webAudioSupport = jswindow.hasProperty("AudioContext") ||
  +        jswindow.hasProperty("webkitAudioContext");
  +    }
  +    return _webAudioSupport;
  +  }
  +
   }
   
   /**
  
positive.code: }
  
  /**
   * Audio source that is streamed in while playing using AudioElement instead of being preloaded.
   */
  class AudioStream extends PlayableAudio {
  
  
negative.code: part of dtmark;
  
  /**
   * Wrapper around a WebAudio AudioContext which is used by DTMark audio classes.
   */
  class AudioEngine {
  
    WebAudio.AudioContext ctx;
  