RFR[S]: 8239014 -XX:-UseEmptySlotsInSupers sometime fails to reproduce the layout of the old code

[Frederic Parain]

Please review this small change that fix the behavior of-XX: -UseEmptySlotsInSupers.

CR: https://bugs.openjdk.java.net/browse/JDK-8239014
Webrev: http://cr.openjdk.java.net/~fparain/8239014/webrev.00/index.html

Thank you,

Fred