Remove dead code

This call to `$.fn.position` was causing an error in IE 8 because the
`offsetParent` was null on the container for some reason. It's not
needed, so this line of code has been removed.

This should fix the test failures in IE 8.

src/js/select2/dropdown/attachBody.js

@@ -128,7 +128,6 @@ define([
 
     var newDirection = null;
 
-    var position = this.$container.position();
     var offset = this.$container.offset();
 
     offset.bottom = offset.top + this.$container.outerHeight(false);