Declared dataset as object for internet explorer 10

Internet explorer 10 crashed when trying to access the dataset property of the audio object.

Author: SirLink

src/loader/filetypes/HTML5AudioFile.js

@@ -148,7 +148,7 @@ var HTML5AudioFile = new Class({
         for (var i = 0; i < instances; i++)
         {
             var audio = new Audio();
-
+            audio.dataset = {};
             audio.dataset.name = this.key + ('0' + i).slice(-2);
             audio.dataset.used = 'false';