Update Frequently Asked Question.md

fix typo.

Fix type cast error with `invokeMethod` method.

The root cause is that dart only returned `Map<dynamic, dynamic>` rather than specific generic type when `invokeMethod` was called. For more specific generic type user can use `cast<String, dynamic>` after the result was returned.

Update format according for flutter's analysis option

add custom dartEntrypoint

# Conflicts:
#	example/lib/simple_page_widgets.dart

# Conflicts:
#	android/src/main/java/com/idlefish/flutterboost/containers/FlutterActivityAndFragmentDelegate.java

merge code

 cherrypick: 最后一个flutter页面关闭的时候回调对Engine的OwnerViewController清空	efea291c	余玠 <xujian.xj@alibaba-inc.com>	2020年3月30日 21:56