It might be trickier than it appears.
The way I see it (but I may be missing something), webfont and font-face creates a font family on runtime thanks to some CSS styling. But how would you get this font-family at edittime ? I'm not sure the editor could emulate it.
Also it would require the dev (the end user) to modify the exported .html to add the informations concerning the creation of the family (and the font files, etc...).
I'm awaiting Ashley's opinion on this one. I agree that it would be a nice built-in feature, but I'm wondering on how it could be implented in the c2runtime in the end.