Another thing to consider in regards to Apple allowing third-party web rendering engines on iOS, aside from somebody needing to take responsibility for the litany of vulnerabilities such a thing would introduce is the sheer size of these things. They’re huge. The Mac version of Firefox is 185MB while Chrome is a whopping 250MB.<p>Apps start getting annoying to download+install at about the 50MB mark… and are people really going to want ~200MB of their device taken up by something as elementary as a web browser? Don’t forget that a large majority of iOS devices in use today are 16GB models.