Log @font-face rules for page

font-face-rules.js

for (var i=0;i<document.styleSheets.length;i++) {
    console.group(document.styleSheets[i].href);
    for (var j=0;j<document.styleSheets[i].cssRules.length;j++)
    {
        var rule =document.styleSheets[i].cssRules[j];
        if (rule instanceof CSSFontFaceRule) {
            console.log(rule.cssText);
        }
    }
    console.groupEnd();
}