c3 does not support moment but only string with a specific format.
We implement .toString on the moment prototype because form widgets does not
use Sao.Date nor Sao.DateTime. This ensures that calling .toString will always
return the ISO format.
And finally the x field type is retrieved from the model instead of the
attribute which is no more filled since changeset 2fc36d9e359b
issue9539
review296221002
Cédric Krier
056e43717e