JS: fix KeyWordIndex convenience constructor
JS: fix KeyWordIndex convenience constructor

Commit 9b5837dbd1a86c9e71bca4902e04eadbb6f876cc has bug as the index of
the arguments can be anywhere in the ArrayList, not neceassrily at index
0, add the offset to the previous start of args to actually skip, not
just pass through and arbitrary list.

Remove another constructor with a similar problem that is unused.

Signed-off-by: Harvey Harrison <eadbd6b462bf3c97df0300a934c12bc2e5d1fe51@gmail.com>

jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim