<Swing Dev> [9] Review request for 8164032 JViewport backing store image is not scaled on HiDPI display

[Alexandr Scherbatiy]

Hello,

Could you review the fix:
   bug: https://bugs.openjdk.java.net/browse/JDK-8164032
   webrev: http://cr.openjdk.java.net/~alexsch/8164032/webrev.00

   The fix scales the JViewport backing store image when graphics 
transform is not identity.

  Thanks,
  Alexandr.