Gtk can have GDK_WINDOWING_X11 and GDK_WINDOWING_WAYLAND at the same time. So I think it would be better to use WTF_PLATFORM_X11 flag than to use GDK_WINDOWING_X11 for future wayland support.
Created attachment 207626 [details] Patch
Thanks for the patch. If this patch contains new public API please make sure it follows the guidelines for new WebKit2 GTK+ API. See http://trac.webkit.org/wiki/WebKitGTK/AddingNewWebKit2API
FWIW, I believe the future plan is to also have concurrent support for both X11 and Wayland protocols in the same build, like the GTK+ toolkit itself.
Comment on attachment 207626 [details] Patch Yeah, since the plan is to be able to enable both and select at runtime, I think this change is probably not worth it. We would need to decide how we want to decide what to enabled, for that.