var isFontFaceSupported = (function(){  
	var 
	sheet, doc = document,
	head = doc.head || doc.getElementsByTagName('head')[0] || docElement,
	style = doc.createElement("style"),
	impl = doc.implementation || { hasFeature: function() { return false; } };
	 
	style.type = 'text/css';
	head.insertBefore(style, head.firstChild);
	sheet = style.sheet || style.styleSheet;
	 
	var supportAtRule = impl.hasFeature('CSS2', '') ?
	        function(rule) {
	            if (!(sheet && rule)) return false;
	            var result = false;
	            try {
	                sheet.insertRule(rule, 0);
	                result = !(/unknown/i).test(sheet.cssRules[0].cssText);
	                sheet.deleteRule(sheet.cssRules.length - 1);
	            } catch(e) { }
	            return result;
	        } :
	        function(rule) {
	            if (!(sheet && rule)) return false;
	            sheet.cssText = rule;
	 
	            return sheet.cssText.length !== 0 && !(/unknown/i).test(sheet.cssText) &&
	              sheet.cssText
	                    .replace(/\r+|\n+/g, '')
	                    .indexOf(rule.split(' ')[0]) === 0;
	        };
	 
	return supportAtRule('@font-face { font-family: "font"; src: "font.ttf"; }');
})();