[13] RFR JDK-8222212:Memory Leak with SwingNode using Drag and Drop function

[Prasanta Sadhukhan]

Hi All,

Please review fix for SwingNode memory leak when SwingNode content has a 
drop target therefore, initiating a DnD. FXDnd holds a strong reference 
to SwingNode thereby preventing it to be disposed.
Proposed fix is to weakreference the swingnode object in FXDnDInteropN 
class.

Bug: https://bugs.openjdk.java.net/browse/JDK-8222212
webrev: http://cr.openjdk.java.net/~psadhukhan/8222212/webrev.0/

Regards
Prasanta