Fix sound not playing in Dartium checked mode.

tools/dom/idl/dart/dart.idl

 // This file introduces / supplements and forces Dart declarations.
 
-[DartSupplemental,
- Constructor]
-interface AudioContext {
-  // TODO(ager): Auto-generate this custom method when the info about retaining
-  // typed arrays is in the IDL.
-  [Custom] void decodeAudioData(ArrayBuffer audioData, AudioBufferCallback successCallback, AudioBufferCallback errorCallback);
-};
-
 [DartSupplemental]
 interface WaveShaperNode {
   // TODO(ager): Auto-generate this custom method when the info about retaining
   // typed arrays is in the IDL.
   [Custom=Setter] attribute Float32Array curve;
 };
 
 [DartSupplemental]
 interface AudioParam {
   // TODO(ager): Auto-generate this custom method when the info about retaining
@@ skipping 460 matching lines @@
 };
 
 
 [DartSupplemental]
 interface EventTarget {
     [DartSuppress] void addEventListener(DOMString type, EventListener? listener, optional (EventListenerOptions or boolean) options);
     [DartSuppress] void removeEventListener(DOMString type, EventListener? listener, optional (EventListenerOptions or boolean) options);
     [Custom] void addEventListener(DOMString type, EventListener? listener, optional boolean options);
     [Custom] void removeEventListener(DOMString type, EventListener? listener, optional boolean options);
 };