RFR: JDK-8204109: JDK-8203945 broke nashorn

[Erik Joelsson]

In my recent cleanup change for the nashorn build, I accidentally 
removed a line that caused the nasgen tool to never run. This is causing 
a bunch of nashorn tests to fail in tier2. I had run tier1-3 on an 
earlier version of the patch, but forgot to rerun after the last edit.

Bug: https://bugs.openjdk.java.net/browse/JDK-8204109
Webrev: http://cr.openjdk.java.net/~erikj/8204109/webrev.01/

/Erik