add createMediaStreamDestination

methods and interface are defined in
http://webaudio.github.io/web-audio-api/ and implemented in chrome

webaudioapi/waa.d.ts

@@ -86,6 +86,11 @@ interface AudioContext {
      */    
     createMediaStreamSource(mediaStream: any): MediaStreamAudioSourceNode;
 
+    /**
+     * Creates a MediaStreamAudioDestinationNode.
+     */
+    createMediaStreamDestination(): MediaStreamAudioDestinationNode;
+
     /**
      * Creates a ScriptProcessorNode for direct audio processing using JavaScript. An exception will be thrown if bufferSize or numberOfInputChannels or numberOfOutputChannels are outside the valid range.
      * It is invalid for both numberOfInputChannels and numberOfOutputChannels to be zero.
@@ -1142,3 +1147,17 @@ interface WaveTable {
  */
 interface MediaStreamAudioSourceNode extends AudioSourceNode {
 }
+
+/**
+ * This interface is an audio destination representing a MediaStream with a single AudioMediaStreamTrack. This MediaStream is created when the node is created and is accessible via the stream attribute. This stream can be used in a similar way as a MediaStream obtained via getUserMedia(), and can, for example, be sent to a remote peer using the RTCPeerConnection addStream() method.
+ *
+ *    numberOfInputs  : 1
+ *    numberOfOutputs : 0
+ *
+ *    channelCount = 2;
+ *    channelCountMode = "explicit";
+ *    channelInterpretation = "speakers";
+ */
+interface MediaStreamAudioDestinationNode extends AudioNode {
+  stream: MediaStream;
+}