Sound: Fixes an issue where loopFull would not return the soundinstance that it looped from

Author: hilts-vaughan

src/sound/Sound.js

@@ -477,7 +477,7 @@ Phaser.Sound.prototype = {
      */
     loopFull: function (volume) {
 
-        this.play(null, 0, volume, true);
+       return this.play(null, 0, volume, true);
 
     },