Pretty sure I heard them say exactly that it was at WWDC. I wrote it down in my notes anyway. ~04:30 in the WWDC video "Introducing the Modern WebKIT API"
It was stated it used 4th tier LLVM JIT (FTL) [0]. Do you have evidence to the contrary? What did you do to test? If you can outline what you did I will be happy to help out and investigate.
Sorry, you probably misunderstood me – WKWebView runs in a separate process and does have a JIT (discussed in that video); JavaScriptCore runs in the same process and does not.
