[12] RFR JDK-8211249:Refactor javafx.swing implementation to get rid of unneeded abstraction layer

[Prasanta Sadhukhan]

Hi Kevin,All,

Please review a cleanup of the abstraction layer done during refactoring 
of fx swing interop implementation.

Bug: https://bugs.openjdk.java.net/browse/JDK-8211249
webrev: http://cr.openjdk.java.net/~psadhukhan/fx/8211249/webrev.0/

Regards
Prasanta