kwalrath
commented
8 years ago The language tour has a bunch of known issues where it needs updating (see #1518). Unfortunately, I only got halfway through them before something more urgent came up. This particular issue is a duplicate of #1475.
PRs would be very welcome...
Section "Adding features to a class: mixins" states "To implement a mixin, create a class that extends Object, declares no constructors, and has no calls to super"
It's outdated since Dart 1.13 and greater supports mixins that can extend from classes other than Object, and can call super()