Adam Barth 3a31f5f772 Give Interval a Curve to apply between start and end
This patch simplifies AnimationTiming and all the AnimatedValue base classes.
Also, make PopupMenu a stateless component because it has no state.

Fixes #1168
2015-10-05 12:10:48 -07:00
..
2015-10-02 23:12:03 -07:00