[9] Review request for 8172554: [macos] deadlock on JFXPanel startup

[Semyon Sadetsky]

Hello Kevin & David,

Please review the fix for jfx9:

bug: https://bugs.openjdk.java.net/browse/JDK-8172554

webrev: http://cr.openjdk.java.net/~ssadetsky/8172554/webrev.01/

JFXPanel initializes JFX on EDT as result EDT and Toolkit thread may 
block each other. The proposed solution do not block EDT while JFX is 
initialized. See other details in the bug.

--Semyon