Fix for unsecure content warning in Internet Explorer.

We encountered unsecure content warnings on SSL sites, even though we had no non-SSL content. Placing a script tag with `src="javascript:void(0);"` makes IE think it's loading through an unsecure protocol. Loading `//:` instead fixed our problem as described [here](http://blog.httpwatch.com/2009/09/17/even-more-problems-with-the-ie-8-mixed-content-warning/).