* ensure `TransitionRoot` component without props transitions correctly
A bit of a weird one, but you can use the `TransitionRoot` component
without any props for transitions themselves (so no real transition can
happen). Even crazier, it can happen that it doesn't even render a DOM
node, but just its children.
At this point, the `TransitionRoot` component is purely there for
orchestration purposes of child components.
Since there is no DOM node in certain situations, the transitions (and
its `onStart` and `onStop` callbacks) won't even happen at all. This
causes a bug (obvious in react strict mode) where children don't
properly mount or the transition component doesn't properly unmount.
* update changelog
Robin Malfait
afc9cb648b