Doing a fresh install of the latest macports (2.0.3-10.6), I executed sudo port install webkit-gtk.
Still the configuration failed, complaining about the missing GAIL-3.0.
The webkit-gtk installed gtk2,
I forced the installation of gtk3 and then 'configure' passed.
It took me a while to understand gail was part of GTK, then to find the way to get the appropriate GAIL installed.
If installation instructions were giving the tip, it would already save time.
Thanks & regards - john
The people who take care of macports don't read this bug tracker. You'll have better luck filing this bug directly on the macports page.