Fix incorrect detection of backward navigation when a visitable appears
Fix incorrect detection of backward navigation when a visitable appears

The appearing visitable's isMovingToParentViewController() will be false
if it's already on the navigation stack when it appears.

turbolinks/turbolinks-ios,turbolinks/turbolinks-ios,turbolinks/turbolinks-ios,turbolinks/turbolinks-ios,turbolinks/turbolinks-ios