Remove AlertIOS

Summary:
This module was merged with `Alert`. Landing the removal now will mean that it is gone from 0.61 which means the deprecation warning will have been there for two full versions.

It will also make it easier to ship D14538298.

Reviewed By: rubennorte

Differential Revision: D14539026

fbshipit-source-id: fb36482324866c277811756cc7461451a1482b23

Libraries/react-native/react-native-implementation.js

@@ -190,13 +190,6 @@ module.exports = {
   get Alert() {
     return require('Alert');
   },
-  get AlertIOS() {
-    warnOnce(
-      'alert-ios',
-      'AlertIOS is deprecated. Use the `Alert` module directly instead.',
-    );
-    return require('Alert');
-  },
   get Animated() {
     return require('Animated');
   },