littlesome 49667db1c8 Fix Alert memory leak
Summary:
1. Using weak container to hold the currently opened alerts.
2. Using weak reference to alertController in action handler block.
3. BTW,  remove the unused vars: _alertCallbacks, _alertButtonKeys.

Test plan (required)

```
- (void)invalidate
{
  for (UIAlertController *alertController in _alertControllers) {
    [alertController.presentingViewController dismissViewControllerAnimated:YES completion:nil];
  }
}
```
Since we use weak container, _alertControllers should only contains the currently opened alerts.

I test this way: Put a breakpoint in invalidate, open the UIExplorer play with the 'Alert' & 'AlertIOS' examples, then fire a reload and see if _alertControllers contains the expected values.
Closes https://github.com/facebook/react-native/pull/10407

Differential Revision: D4078649

Pulled By: lacker

fbshipit-source-id: 8509e7e7142379a81d5b28c9067c085bad8bb5cb
2016-10-25 17:28:49 -07:00
..
2016-10-25 17:28:49 -07:00
2016-10-10 12:13:46 -07:00
2016-05-11 06:27:29 -07:00
2016-09-06 02:43:40 -07:00