[Unified Swing/Fx threading] don't schedule an event dispatching from the event dispatch thread

In the unified Swing/Fx threading mode, when an even is sent (DefaultKeyboardFocusManager.sendMessage) it is scheduled for dispatching instead of dispatching it straight away. This breaks the focus functionality.

Use the attached test to reproduce. Click on the fx button, focus should be transferred to the swing button, but it isn't.