Revert "Disable webkit2gtk integration"

This reverts commit ce4ed6b.

The needed change has reached stable and unstable Nixpkgs channels.
No need to duplicate it here now.

overlays/emacs.nix

@@ -16,7 +16,7 @@ let
       super.emacs
       ([
 
-        (drv: drv.override ({ srcRepo = true; withXwidgets = false; } // args))
+        (drv: drv.override ({ srcRepo = true; } // args))
 
         (
           drv: drv.overrideAttrs (