FabioLolix [1] filed a deletion request for webkitgtk-sharp-git [2]: Always missed webkitgtk in depends, C# bindings for webkitgtk (3.0), 18 commits history and last version released on 2014-06-15. sparkleshare-git which is severely outdated (last update 2018-03-28) depends on this but it is not actually needed, sparkleshare is in [Extra]
[1] https://aur.archlinux.org/account/FabioLolix/ [2] https://aur.archlinux.org/pkgbase/webkitgtk-sharp-git/