RFR [8u60]: 8073944: Simplify ArgumentsExt and remove unneeded functionallity

[Stefan Johansson]

Hi,

Please review this small changes for:
https://bugs.openjdk.java.net/browse/JDK-8073944

Webrev:
http://cr.openjdk.java.net/~sjohanss/8073944/hotspot.00/

Summary:
The removed functionality was added as part of JDK-8057623, but is no 
longer needed.

Thanks,
Stefan