[9] Review request for 8166591 [macos 10.12] Trackpad scrolling of text on OS X 10.12 Sierra is very fast (Trackpad, Retina only)

[Alexander Scherbatiy]

Hello,
Could you review the fix:
  bug: https://bugs.openjdk.java.net/browse/JDK-8166591
  webrev: http://cr.openjdk.java.net/~alexsch/8166591/webrev.02

  This issue has been risen and investigated by JetBrains team in the 
email:
http://mail.openjdk.java.net/pipermail/awt-dev/2016-September/011991.html

  MacOS Sierra 10.12 sends many scroll events with values close to zero 
when the trackpad is used. The small scroll values are rounded to +1 or 
-1 so one line scroll would be possible. It leads that many small scroll 
events causes fast scrolling.

  The proposed fix accumulates scroll values from the trackpad until 
they exceed some threshold  values. Only after that 
MouseWheelEvent.wheelRotation value is set. Mouse wheel scroll events 
are handled as before, small values are just rounded to + or -1.

  Thanks,
  Alexandr.