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

http://webaudio.github.io/web-audio-api/#the-audionode-interface

This does not change observable behavior, as toInt32 in V8Binding.cpp
returns 0 for undefined.

Review URL: https://codereview.chromium.org/816453003

git-svn-id: svn://svn.chromium.org/blink/trunk@187392 bbb929c8-8fbe-4397-9dbb-9b2b20218538
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioNode.idl b/third_party/WebKit/Source/modules/webaudio/AudioNode.idl
index 74ac3404..9ba9f6e5 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioNode.idl
+++ b/third_party/WebKit/Source/modules/webaudio/AudioNode.idl
@@ -40,9 +40,9 @@
     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;