Well, UIWebView (the standard web view, pre iOS8) does not have Nitro, but WKWebView (introduced in iOS8) has Nitro. The only problem is that while they are similar, the WKWebview API is not feature complete with UIWebView, leading to a lack of adoption from big players such as Chromium.

[0]: https://code.google.com/p/chromium/issues/detail?id=423444