Sample project for rdar://25087688

If setHidden:YES has been called more than two times then setHidden:NO needs to be called more than once before the subview shows again.

1. Create a UIStackView with a few arranged subviews
2. Call setHidden:YES on one of the arranged subviews within an animation block
3. Call setHidden:YES two more times
4. Call setHidden:NO on the subview

The subview is visible and isHidden returns NO

The subview is still hidden and isHidden returns YES

Tested on iPhone 6S and simulator running iOS 9.2.1