iOS 关闭UIAlertController之后，原FBFlutterViewContainer点击无响应

版本：'v3.0-null-safety-preview.18'

问题：iOS 14.4.2，使用当前FBFlutterViewContainer直接present一个原生UIAlertController弹窗，关闭弹窗之后，原FBFlutterViewContainer点击无任何响应。

弹窗关闭后，FB日志截图：

@ColdPaleLight 麻烦大佬帮忙看看啊，关闭弹窗之后，从flutter_boost打的log看会把之前的flutter页面给pop掉？

Reproduce the issue on iOS 14.4.2 using FBFlutterViewContainer, presenting and dismissing a native UIAlertController. Start by reviewing the FlutterBoost logs mentioned in the report and verify whether the Flutter page is popped; done means the original container still responds to taps after the alert closes.

Written by the indexing model from the issue text.