RFR (XS): 8081668: fix Nashorn ant externals command

[Michael Haupt]

Dear all,

please review and sponsor this small fix:
Bug: https://bugs.openjdk.java.net/browse/JDK-8081668
Webrev: http://cr.openjdk.java.net/~mhaupt/8081668/webrev.00

Recent changes in the Showdown project on Github led to dependencies no longer being available for download, which would lead to failures in fresh Nashorn workspaces. Falling back to a revision of the project that has these files fixes this.

Tested in a fresh workspace.

Thanks,

Michael

-- 

 <http://www.oracle.com/>
Dr. Michael Haupt | Principal Member of Technical Staff
Phone: +49 331 200 7277 | Fax: +49 331 200 7561
Oracle Java Platform Group | HotSpot Compiler Team 
Oracle Deutschland B.V. & Co. KG, Schiffbauergasse 14 | 14467 Potsdam, Germany
 <http://www.oracle.com/commitment>	Oracle is committed to developing practices and products that help protect the environment