There is a browser called BOWSER for iOS that does support WebRTC. (It's made by Ericsson)
In theory, Construct2 multiplayer games should work on iOS inside of the Bowser browser. (According to Ericsson)
In my testing, I've not been able to get Construct2 mutliplayer apps to work in Bowser on iOS. (I've tried the standard demo apps from C2).
Anyone else had better luck? (You can download Bowser from app store for free)
Ashley - if you are reading this - have you tried it?