[whatwg] Need document.available_fonts() call

[Eitan Adler]

> Please note there's a rather strong privacy issue here. I don't want a
> web page to be able - without my prior consent - to query the list of
> fonts available in my system.

You already have this problem if a website were to create a list of
elements with a list of different fonts and use Javascript to
determine which font is being displayed. [1]

I'm not advocating opening another hole just because one already
exists - I'm just pointing this out.

[1] http://www.lalit.org/lab/javascript-css-font-detect