RFR: JDK-8208471: nsk/jdb/unwatch/unwatch002/unwatch002.java fails with "Prompt is not received during 300200 milliseconds"

[Gary Adams]

The corrupted output has been identified due to the "Boolean[1]"
being misrecognized as a compound prompt.

The proposed fix waits for the correct prompt before
advancing to the next command.

   Webrev: http://cr.openjdk.java.net/~gadams/8208471/webrev/
   Issue: https://bugs.openjdk.java.net/browse/JDK-8208471

Testing is in progress.