[9] API Review Request: 8144556 - Add support to allow user specified rendering order

[Chien Yang]

Hi Kevin and all,

Please review the following new API proposal to add a priorityOrder 
property to Node:

JIRA: https://bugs.openjdk.java.net/browse/JDK-8144556

Here is a prototype of the implementation with a simple toy example if 
you wish to play with:

Webrev: http://cr.openjdk.java.net/~ckyang/JDK-8144556/prototype/

I will be on vacation for a week starting tomorrow so my response may be 
delayed.

Thanks,
- Chien