Hi,
After a brand new installation with the gnome-stage, I have done an emerge -auDN @world --with-bdeps="y".
The compilation of net-libs/webkit-gtk failed (it took some times, and from time to time were blocking screen).
I have done all the others compilations requested one by one without issue, net-libs/webkit-gtk is requested with the @world compilation and failed everytime (tried 3 times). I gave a try with "MAKEOPT="j1" emerge {}1 net-{-}libs/webkit-gtk" but the same problem appears.
I attached build.log (in .zip as it's more than 10Mo), environment, and 2 text files that could be of help.