Code Review Request For 8137252: JavaFX StackPane bounds not updated

[Chien Yang]

Hi Kevin and Jonathan,

Please review the proposed fix and the detail of the fix is recorded in 
the JIRA:

JIRA: https://bugs.openjdk.java.net/browse/JDK-8137252
Webrev: http://cr.openjdk.java.net/~ckyang/JDK-8137252/webrev.00/

Thanks,
- Chien