Fix for DYNJS-102. There is now a global `argv` object.

    $ ./run-repl argv.js arg1 arg2
    Arg count: 3
    Arg 0: foo.js
    Arg 1: arg1
    Arg 2: arg2

    $ cat argv.js
    print("Arg count: " + argv.length);

    for (i = 0; i < argv.length; i++) {
      print("Arg " + i + ": " + argv[i]);
    }