Adding test for IE9 in iframes

Internet Explorer 9 supports css3 media queries, but not within frames when the CSS containing the media query is in an external file (this appears to be a bug in IE9 — see http://stackoverflow.com/questions/10316247/media-queries-fail-inside-ie9-iframe). I've modified the script to add a test for IE9 and check if the page is within an iframe, and run the script if those conditions are met. Otherwise the script bails because respond.mediaQueriesSupported returns true for IE9.