JavaScriptAudioNode is an EventTarget.

client/dom/idl/dart/webkit-supplemental.idl

 /**
  */
 
 // Supplements and corrects errors in WebKit IDL to better align with browser
 // neutral APIs.
 
 module default {
   Node implements events::EventTarget;
   MessagePort implements events::EventTarget;
   EventSource implements events::EventTarget;
   Window implements events::EventTarget;
   ApplicationCache implements events::EventTarget;
   XMLHttpRequest implements events::EventTarget;
   XMLHttpRequestUpload implements events::EventTarget;
   Notification implements events::EventTarget;
   AbstractWorker implements events::EventTarget;
   WorkerContext implements events::EventTarget;
   SVGElementInstance implements events::EventTarget;
   WebSocket implements events::EventTarget;
+  JavaScriptAudioNode implements events::EventTarget;
 }