RFR 8144473: Nashorn code assumes NashornCallSiteDescriptor always

[Sundararajan Athijegannathan]

Please review http://cr.openjdk.java.net/~sundar/8144473/ for 
https://bugs.openjdk.java.net/browse/JDK-8144473

Piggybacking a dynalink pluggable linker sample to translate 
underscore_separated names to CamelCase names.
The bug in nashorn was found when attempting to use that linker. Nashorn 
call site descriptors failed (before the current fix)

Thanks,
-Sundar