Rotated HScrollBar with constraints draws incorrectly

Found in SDK 19859.

Steps to reproduce:
1. Compile and run the attached app "TH12979.mxml"

Actual Results: the HScrollBar and the blue Rect are different size and location

Expected Results: the HScrollBar and the blue Rect have the same size and location

The Rect and the HScrollBar have identical Left, Right, Top, and Bottom properties so I would expect them to have the same size and location.

Workaround: Give any explicit width & height to the HScrollBar.