Retainer box widget causes progress bars to render incorrectly

Retainer boxes are currently causing progress bars to render incorrectly. This looks to be related to [Link Removed] which is fallout from the changes to retainer widget transform calculation introduced in CL# 14300227. We may need to revert this change and look for an alternative solution to the transform issues described in the associated UDN post ([Link Removed]).

1. Create a progress bar, and wrap it in a retainer widget
2. Set the progress bar to 50%
3. Resize the viewport during PIE, and note that the bar flickers between 50% and 100%