Problem
With the latest versions of firefox, a javascript file fail to load from an external site such as google using the following code: <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.10.3/jquery-ui.js"></script>
The connection was secure running on HTTPS. However the connection to load the javascript file was not secure running purely on HTTP.
Solution
To get the javascript file to load properly I simply changed the SRC URL to use HTTPS as shown below:
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.10.3/jquery-ui.js"></script>