ReactAnimationGroup failing to re-add components/reverse animations.

[Cartas]

Please see: http://jsfiddle.net/LvkNt/10/ and do the following:

1. Click 'Toggle' to make the list-item fade into view.
2. Double-click/Spam-click the 'Toggle' button again to make the item fade-out of view.
3. Click 'Toggle' again to try to make the component come back into view.

You'll see that the item doesn't come back! If you check the HTML, you can see that the list-item is still there, with the class name "example-leave example-leave-active".

I suspect that React should reverse the animation elegantly in the case of the same component being re-added in the render function during a leave transition.

[sophiebits]

Thanks, I was going to point you to #642 but I see that you're the author of it!

[Cartas]

Hehe, I thought perhaps it'd be best if I made a proper Issue (with JSFiddle example!) rather than just rudely posting Pull Requests! :)