[8] Review request for 8028212 Custom cursor HiDPI support

[Alexander Scherbatiy]

Hello,

Could you review the fix:
   bug: https://bugs.openjdk.java.net/browse/JDK-8028212
   webrev: http://cr.openjdk.java.net/~alexsch/8028212/webrev.00

   - MultiResolutionImage interface is used from the fix 8011059
   - NSImage with representations are created for the multi-resolution 
cursor
   - NSImage representations are rescaled to the base cursor size

Thanks,
Alexandr.