[9-dev] Request for review: RT-40607: Mac resize cursors are wrong

[Morris Meyer]

Kevin and David,

Please review my changes to GlassCursor.m to fix the lack of proper Mac 
NW, SW, SE and NE resize cursors.

As the look-up for these cursors was a little involved, I opted to use a 
one-time cache so as not to induce any noticeable visual lag when 
setting these cursors.

Thanks much,

        --morris

JIRA - https://javafx-jira.kenai.com/browse/RT-40607
WEBREV - http://cr.openjdk.java.net/~morris/RT-40607.01/