[9] Review request: 8166565 [hidpi] a flickering scrollbar when using Caspian style sheet

[Jim Graham]

JBS: https://bugs.openjdk.java.net/browse/JDK-8166565
webrev: http://cr.openjdk.java.net/~flar/JDK-8166565/webrev.00/

I made the 6 new snapXY() methods in Region public for convenience here.  They are all new for 9 and had been protected, 
now they are public.

As noted in the bug report comment, there are a couple of places where I could not decide if the call should be for 
snapFooX() or snapFooY() and made a best guess and added a comment.  Please advise.

Also, advise if someone else should be CC'd on the review thread...?

			...jim