Replace [Default=Undefined] with per-spec syntax for AudioNode

Source/modules/webaudio/AudioNode.idl

Index: Source/modules/webaudio/AudioNode.idl
diff --git a/Source/modules/webaudio/AudioNode.idl b/Source/modules/webaudio/AudioNode.idl
index 74ac3404e19f52c0146e0bc6df930c5fae04c888..9ba9f6e5687e1bada273aa0fcd9f558af4bc25f2 100644
--- a/Source/modules/webaudio/AudioNode.idl
+++ b/Source/modules/webaudio/AudioNode.idl
@@ -40,9 +40,9 @@ enum ChannelInterpretation {
     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 = 0, optional unsigned long input = 0);
+    [RaisesException] void connect(AudioParam destination, optional unsigned long output = 0);
+    [RaisesException] void disconnect(optional unsigned long output = 0);
     readonly attribute AudioContext  context;
     readonly attribute unsigned long numberOfInputs;
     readonly attribute unsigned long numberOfOutputs;