Steps to Reproduce

1. User FlutterEngineGroup create new flutter engine
2. Say we have Activity1 associated with flutter engine 1, Activity2 associated with flutter engine 2
3. when user open the app, Activity1 is created and it create flutter engine 1 to render the view
4. user interact with Activity1 to open Activity2
5. Activity2 is created and it created flutter engine 2 to render view
6. user navigate back
7. Activity2 is destroy triggering flutter enige 2 destroy
8. User back to Activity1
9. User interact with Activity1 and no any response

Expected results:
User can continue interact with Activity1

Actual results:
User can not continue interact with Activity1