IDL: make optional arguments (without default) explicit sometimes

Source/modules/webaudio/AudioNode.idl

 /*
  * Copyright (C) 2010, 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 23 matching lines @@
 };
 
 // http://webaudio.github.io/web-audio-api/#idl-def-AudioNode
 
 [
     Conditional=WEB_AUDIO,
     Custom=Wrap,
     GarbageCollected,
 ] interface AudioNode : EventTarget {
     // FIXME: AudioNode argument should not be nullable
-    [RaisesException] void connect(AudioNode? destination, [Default=Undefined] optional unsigned long output, [Default=Undefined] optional unsigned long input);
-    [RaisesException] void connect(AudioParam destination, [Default=Undefined] optional unsigned long output);
-    [RaisesException] void disconnect([Default=Undefined] optional unsigned long output);
+    [RaisesException] void connect(AudioNode? destination, optional unsigned long output, optional unsigned long input);
+    [RaisesException] void connect(AudioParam destination, optional unsigned long output);
+    [RaisesException] void disconnect(optional unsigned long output);
     readonly attribute AudioContext  context;
     readonly attribute unsigned long numberOfInputs;
     readonly attribute unsigned long numberOfOutputs;
     [RaisesException=Setter] attribute unsigned long         channelCount;
     [RaisesException=Setter] attribute ChannelCountMode      channelCountMode;
     [RaisesException=Setter] attribute ChannelInterpretation channelInterpretation;
 };