199310695f
This PR mirrors virtual a11y tree of embedded platform views in the Flutter a11y tree. Non virtual hierarchies are not currently supported. Only works on Android versions earlier than Android P as it relies on reflection access to hidden system APIs which cannot be done starting Android P. A11y is not yet working as we also need to delegate a11y events from the platform view to the FlutterView. This will be done in a following PR to keep the change size a little saner.