<AWT Dev> [9] Review request: 8042752 [macosx] NSEvent instances leak throw JNI local references

[Petr Pchelko]

Hello, AWT Team.

Please review the fix for the issue:
https://bugs.openjdk.java.net/browse/JDK-8042752
The fix is available at:
http://cr.openjdk.java.net/~pchelko/9/8042752/webrev/

The problem's that we are creating NSEvent instances from native on Appkit thread,
but not removing the local references. It's hard to create a regression test, because the 
leak is not too big, so the test execution would take too long until we get OOM.

Thank you.
With best regards. Petr.