I will just say: "[a]t the moment webkit2gtk in main is only used for displaying content that is relatively controlled" is a misunderstanding. Unless you're planning to get rid GNOME Shell's captive portal helper, then WebKit is going to be displaying whatever the local wireless network wants it to, whenever the local wireless network wants it to do so, without user intervention. (And with so many websites using HSTS nowadays, which breaks captive portals, you really don't want to disable the portal helper.)
I will just say: "[a]t the moment webkit2gtk in main is only used for displaying content that is relatively controlled" is a misunderstanding. Unless you're planning to get rid GNOME Shell's captive portal helper, then WebKit is going to be displaying whatever the local wireless network wants it to, whenever the local wireless network wants it to do so, without user intervention. (And with so many websites using HSTS nowadays, which breaks captive portals, you really don't want to disable the portal helper.)