Fixed webkitAudioContext patch. Refs #38

The patch actually broke newer Safari implementation.

assets/js/lib/webkit-audiocontext-patch.js

@@ -2,47 +2,54 @@
  * Patch to port old implementation of `webkitAudioContext`
  * to standards based `audioContext`.
  *
- * Props to Lajos György Mészáros <[email protected]> for this patch.
+ * Props to Lajos György Mészáros <[email protected]> for this patch, 
+ * although some edits were needed to make it work.
  * @see https://github.com/meszaros-lajos-gyorgy/meszaros-lajos-gyorgy.github.io/blob/master/microtonal/monochord/js/webkit-audio-context-patch.js
  */
 
-/* globals OscillatorNode */
-
 "use strict";
 
 module.exports = function(){
+	var AudioContext,
+		OscillatorNode,
+		oldStart,
+		oldStop;
+
 	if( !window.hasOwnProperty("AudioContext") &&
 	    window.hasOwnProperty("webkitAudioContext") ){
-		var a = window.AudioContext = window.webkitAudioContext;
+		AudioContext   = window.AudioContext = window.webkitAudioContext;
+		OscillatorNode = window.OscillatorNode;
 
-		if(!a.prototype.hasOwnProperty("createGain")){
-			a.prototype.createGain = a.prototype.createGainNode;
+		if(!AudioContext.prototype.hasOwnProperty("createGain")){
+			AudioContext.prototype.createGain = AudioContext.prototype.createGainNode;
 		}
 
 		if(!OscillatorNode.prototype.hasOwnProperty("start")){
 			OscillatorNode.prototype.start = OscillatorNode.prototype.noteOn;
 		}
+
 		// make the first parameter optional for firefox <30
-		var oldStart = OscillatorNode.prototype.start;
-		OscillatorNode.prototype.start = function(t){
-			oldStart(t || 0);
+		oldStart = OscillatorNode.prototype.start;
+		OscillatorNode.prototype.start = function(t = 0){
+			oldStart.call(this, t);
 		};
 
 		if(!OscillatorNode.prototype.hasOwnProperty("stop")){
 			OscillatorNode.prototype.stop = OscillatorNode.prototype.noteOff;
 		}
+
 		// make the first parameter optional for firefox <30
-		var oldStop = OscillatorNode.prototype.stop;
-		OscillatorNode.prototype.stop = function(t){
-			oldStop(t || 0);
+		oldStop = OscillatorNode.prototype.stop;
+		OscillatorNode.prototype.stop = function(t = 0){
+			oldStop.call(this, t);
 		};
 
 		Object.defineProperty(OscillatorNode.prototype, "type", {
-			get : function(){
+			get: function() {
 				return ["sine", "square", "sawtooth", "triangle", "custom"][this.type];
 			},
-			set : function(type){
-				this.type = OscillatorNode.prototype[type.toUpperCase()];
+			set: function(type) {
+				this.type = OscillatorNode.prototype[type.toUpperCase()] || type;
 			}
 		});
 	}