hello Kinou, due to apple's restrictive policies unfortunately it is not possible to implement & offer independent third-party browsers for idevices.
mozilla is prohibited to bring the rendering & javascript engine of firefox onto iOS, since apple is only allowing the use of its own webkit in the terms & conditions for developers - as long as this is the case, firefox and its addon ecosystem cannot be ported to iOS devices.

http://www.pcmag.com/article2/0,2817,2416461,00.asp

Mozilla did have a experimental browser called Junior but even then it did not use the Gecko engine due to the said Apple restrictions.