RFR 8170565: JSObject call() is passed undefined for the argument 'thiz'

[Art Fiedler]

This seems to be working as expected. I tested your modifications on jdk8
nashorn-dev

Good catch Hannes! Please review the updated webrev :
> http://cr.openjdk.java.net/~sundar/8170565/webrev.01/
>
> PS. Had to use Function.prototype.call.call to pass undefined this
> explicitly (as JSObject.call can't be called from script).
>
> -Sundar