Code Review Request For RT-34226: Shading of PhongMaterial Boxes appears unnatural

[Chien Yang]

Kevin and Jim,

   Please review this simple fix. I have also included the report test case 
this change:

JIRA: https://javafx-jira.kenai.com/browse/RT-34226
Webrev: http://cr.openjdk.java.net/~ckyang/RT-34226/webrev.00/

Thanks,
- Chien