When a public component uses one JavaScript engine over another it is probably not a bug or an oversight. My guess is it is an internal dependency and schedulin

When a public component uses one JavaScript engine over another it is probably not a bug or an oversight. My guess is it is an internal dependency and scheduling issue at Apple. The team behind UIWebView is probably downstream from the Safari/Nitro team and they didn't get the new bits in time to ship with 4.3. Full screen mode may well depend on UIWebView and not the Safari app components.