#8 JS asset doesn't work in IE

- using `Event` constructor instead of `CustomEvent` constructor for IE 11 compability

Author: zipper

src/assets/async.nette.ajax.js

@@ -17,7 +17,7 @@
 				$.nette.ajax({
 					url: $this.data('asyncLink') || $this.attr('href'),
 					off: ['history', 'unique']
-				}, $this, new CustomEvent('asyncLoad'));
+				}, $this, new Event('asyncLoad'));
 			});
 		}
 	});