[9] Code Review Request For 8157350: Encapsulate impl_ methods in Shapes related classes

[Chien Yang]

Hi Kevin,

Please review the proposed fix as we have discussed.

JIRA: https://bugs.openjdk.java.net/browse/JDK-8157350
Webrev: http://cr.openjdk.java.net/~ckyang/JDK-8157350/webrev.00/

Thanks,
- Chien