RFR 8157953: JShell tests: reenable ToolBasicTest

[Robert Field]

Please review.

Bugs:

     8157953: JShell tests: reenable ToolBasicTest
     https://bugs.openjdk.java.net/browse/JDK-8157953

     8080883: JShell tool: tool does not report errors if -startup and 
-nostartup flags are specified
     https://bugs.openjdk.java.net/browse/JDK-8080883

Webrev:

     http://cr.openjdk.java.net/~rfield/8157953v0.webrev/

Thanks,
Robert