The Ajax throbber disappears if added to a select list

Problem/Motivation

The Ajax throbber disappears if added to a select list

Steps to reproduce

1. Build a form with the select list that triggers an Ajax event.
2. Open the form and trigger an event.
3. The progress throbber isn't shown to the user.

Proposed resolution

The issue is in ajax.js in Ajax.prototype.setProgressIndicatorThrobber method.

When this method adds throbber to the item it tries to append throbber inside the element instead of adding it after a select list.
So, it seems to me that we need to replace the condition on line 103 with this one if ($element.is('input') || $element.is('select'))