Use CSS Font Loading API when supported by browser.

[ChALkeR]

See https://developer.mozilla.org/en-US/docs/Web/API/CSS_Font_Loading_API.
That page states that it works in Chrome since 35.0 and in Firefox since 41.0.

http://www.w3.org/TR/css-font-loading/
https://drafts.csswg.org/css-font-loading/
http://www.w3.org/TR/css-font-loading/#font-face-set-css