[8] Review request for 7196547: [macosx] Implement dead key detection for KeyEvent

[Alexander Scherbatiy]

bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7196547
webrev: http://cr.openjdk.java.net/~alexsch/7196547/webrev.00/

The characters method from the NSEvent class returns an empty string for 
dead keys.
The fix uses the UCKeyTranslate() method  to know a dead key state from 
the key code and key modifiers on the first step,
and  dead key state and space key to know the dead key char actual value 
on the second step.

Thanks,
Alexandr.