[8u] Review Request: RT-36838 - Strange behavior of TreeItem's disclosure arrow // expanded/collapsed state not reflected correctly

[David Grieve]

Per Kevin's instructions, the previous changeset for RT-36838 was backed 
out in order to resolve RT-36995. I've attached a new webrev to RT-36838 
which is  an improved fix for RT-36838 and which also ensures RT-36995 
doesn't regress. These changes won't be pushed until after M4 integration.

http://cr.openjdk.java.net/~dgrieve/RT-36838/webrev.02/
https://javafx-jira.kenai.com/browse/RT-36838