you're right. this code wasn't installed a packaged app in Firefox Nightly on desktop. but then I changed the `navigator.mozApps.installPackage` call to `navigator.mozApps` and it installed the packaged app on desktop successfully.

`navigator.mozApps.installPackage` exists and is available to use, but it fires an `ondownloaderror` event. this seems really bad. I searched bugzilla but I couldn't find anything relevant. this [blog post](http://tosbourn.com/2013/09/firefox-os/navigator-mozapps-installpackage-will-no-longer-work-use-navigator-mozapps-install/) was the only thing I could find one. where did you hear about `navigator.mozApps.installPackage` being deprecated in favour of ``navigator.mozApps.install`?

we most definitely need to file a bug about this and talk to platform folks. we could listen to `ondownloaderror` and try installing with `navigator.mozApps.install` if it doesn't work, but that seems shitty.