I have been struggling with this just today. What is sure, is that you cannot execute any JS script by using url method no more.
I found a sollution to add edit or view specyfic websites cookies by faking them.
I own jailbroken iPad so all I had to do was to edit hosts file in /etc/ location and redirect needed domain to my own local php server and then I could do whatever I want.
Of course, not everybody use jailbroken device, so I think other similar method would be to run dnsspoof in your local network and do the same but it will be probably little more difficult.
I had to do this because I have older version of iOS system (10.3.1) which does not handle latest CSS standard correctly and one of my favorite websites put huge alert about cookies and EU acceptance, and I wasn't able to click that d*mn AGREE button (was overflown by some text). Because of that I couldn't surf that website at all.
So I added cookie which tells website that I already clicked agree :D then I reverted hosts file to previous state and voila
Hope that'll help somebody