fix chrome err with mic input

TypeError: Failed to execute 'webkitGetUserMedia' on 'Navigator': The value provided is neither an array, nor does it have indexed properties.

Tried changing optional `[]` to optional `{}` and didn't work, so deleted line instead
Firefox seems to continue to work

pitchdetector.js

@@ -59,7 +59,6 @@ function getLiveInput(context,callback){
 	                    "googNoiseSuppression": "false",
 	                    "googHighpassFilter": "false"
 	                },
-	                "optional": []
 	            },
 	        }, function(stream){
 	        	var liveInputNode = context.createMediaStreamSource(stream);
@@ -533,4 +532,4 @@ if(typeof module !== 'undefined') {
 } else {
 	window.PitchDetector = PitchDetector;
 }
-})();
+})();