Fallback for browsers that don't support srcdoc for iframes

srcdoc-shim.js

(function() {
    if(!('srcdoc' in document.createElement('iframe'))) {
        var iframes = document.getElementsByTagName('iframe');

        for(var i = 0, len = iframes.length; i < len; i++) {
            var iframe = iframes[i];

            if(iframe.hasAttribute('srcdoc')) {
                iframe.src = 'javascript: window.frameElement.getAttribute(\'srcdoc\');';
            }
        }
    }
})();