The new version of React Native finally removed this export. We're using an ancient version of react-native-firebase, context on why here.
The right long-term solution is to migrate all of our Android notifs logic to be using our own modules, but in order to unblock the React Native update I'm just patching this now.
Depends on D5923
Can we have a const instead of a function that tells if it is Safari? We can avoid having to detect the browser multiple times, as this fact doesn't change through the lifetime of the app.