Replace features/unsupported-browser SET_UNSUPPORTED_BROWSER with features/base/lib-jitsi-meet SET_WEBRTC_READY
The error raised by JitsiMeetJS.init() is already in the state of
features/base/lib-jitsi-meet so it's not a good design to store the same
error in the state of features/unsupported-browser.
On RN we don't use the global APP object, so don't save the store there unless
it's defined, which is the case in the current web version. Also, check for
undefined explicitly, since a "if (!APP)" check will throw a ReferenceError.
Lib-jitsi-meet uses jQuery's .append method to manipulate Jingle. The
method in question invokes the getter and setter of Element.innerHTML.
Unfortunately, xmldom which we use in React Native to polyfill DOM does
not polyfill Element.innerHTML. So polyfill it ourselves.
Turns out React Native's timers (setTimeout / setInterval) don't run while the
app is in the background: https://github.com/facebook/react-native/issues/167
This patch replaces the global timer functions with those from the
react-native-background-timer package, which work in the background.
These timers won't magically make an application work in the background, but
they will run if an application already happens to run in the background. That's
our case while in a conference, so these timers will run, allowing XMPP pings to
be sent and the conference to stay up as long as the user desires.