I haven't been able to emerge webkit-gtk for a few months now. The error is:
$ sudo cat /var/tmp/portage/net-libs/webkit-gtk-9999/temp/aclocal.out
***** aclocal *****
***** PWD: /var/tmp/portage/net-libs/webkit-gtk-9999/work/webkit-gtk-9999
***** aclocal -I autotools
aclocal-1.11: couldn't open directory `autotools': No such file or director
Thanks for providing these ebuilds in your overlay, BTW.