All* the in app web browsers on iOS are effectively Safari (yes, even Chrome). In one way it is actually a cut down version of Safari, as for security reasons the in app browsers only get to use the old style Javascript engine (if they were allowed to use the new style one then malicious content would have a far more interesting attack surface than it does with the old style one).

* ok, not all, there are a handful of iOS web browser where the parsing/rendering happens on a server somewhere and sends the rendered pages down to a local display app, allowing them to support Flash and the like that Safari doesn't support