[8u60] Review request for RT-39859: NSInternalInconsistencyException Crash

[Morris Meyer]

Kevin and Dave,

Please review this fix for RT-39859.  The fix was to check to make sure 
the submenu item is contained within the menu prior to trying to delete 
it from the menu.

Thanks!

        --morris

WEBREV - http://cr.openjdk.java.net/~morris/RT-39859.01a/
JIRA - https://javafx-jira.kenai.com/browse/RT-39859