8165211: JShell: Fix completion analysis problems

[Robert Field]

Please review....

Bugs:

      JShell: Fix completion analysis problems
      https://bugs.openjdk.java.net/browse/JDK-8165211

Which includes these two sub-tasks (previously separate bugs):

      JShell: incorrect completion analysis for class literals
      https://bugs.openjdk.java.net/browse/JDK-8130454

      JShell: Completion detection: "new" constructor reference 
considered incomplete
      https://bugs.openjdk.java.net/browse/JDK-8080071

Webrev:

      http://cr.openjdk.java.net/~rfield/8165211v0.webrev/

Thanks,
Robert