Updating the UI (in the attached example, setting text on a Label) while the Stage is iconified is not reflected when the Stage is restored.

To reproduce:
- run the attached code sample
- after the window is iconified and then restored, the label should read "Updated while iconified", but it reads "Initial State".
- resize window to force a redraw, observe the label changing to "Updated while iconified"

First reported:
https://www.reddit.com/r/JavaFX/comments/1j8ibpf/platformrunlater_not_updating_the_content_when/

Reproduced on Windows and macOS.