<AWT Dev> [9] Review Request: JDK-8035147 [macosx] Drag and Drop tests are failing with -Xchech:jni

[Petr Pchelko]

Hello, AWT team.

Please review the fix for the issue:
https://bugs.openjdk.java.net/browse/JDK-8035147
The fix is available at: 
http://cr.openjdk.java.net/~pchelko/9/8035147/webrev.00/

The problem was that we were creating global references in the wrong place - after redispatching them to the Appkit thread and not before.
Also I've made a small refactoring to pass the drag image ptr to native directly intead of making an upcall to get it from an object.

Thank you.
With best regards. Petr.