As a developer, I want to be able to simulate IAP in FF OS Simulator by setting my location or other changing other regional settings.
\n is working on this and it should be done by the end of Q1.
Issue being tracked here, follow along! https://github.com/mozilla/r2d2b2g/issues/277
and the thread from from the dev.webapps developer list: https://groups.google.com/forum/#!topic/mozilla.dev.webapps/phGFqhXrP6A
Sorry I didn't update this bug. This has been fixed for quite some time now.