Comment 75 for bug 1189850

(In reply to comment #53)
> Reading
> http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/www-client/firefox/
> firefox-19.0.2.ebuild?view=markup it seems that the use of system-cairo has
> been dropped. Which is a shame.

And the last one, you can find sources of eclasses in your $PORTDIR/eclass dir which is most probably /usr/portage/eclass.

P.S. sorry for a burst of comments.