RFR 8080069: JShell: Support for corralled classes

[Robert Field]

The ability to corral classes has been a long desires feature, now it 
was required to to fix a bug in dependent overloaded methods.

Please review at your earliest convenience to unblock the other work.

Bug:
     8080069:   https://bugs.openjdk.java.net/browse/JDK-8080069

Webrev:
     http://cr.openjdk.java.net/~rfield/8080069v0/

Thanks,
Robert