eo: there is no reason to equip for calls to classes

calls to classes are not needed anymore, since class inheritance is not
a thing anymore. After removing is_obj from the function the compile can
optimize the code better, since assignments to fields are not
conditionally anymore.

Reviewed-by: Carsten Haitzler (Rasterman) <rasterman.com>
Reviewed-by: Stefan Schmidt <stefan@datenfreihafen.org>
Differential Revision: https://phab.enlightenment.org/D11591