[FIX] web: more precise textarea autoresize
[FIX] web: more precise textarea autoresize

Setting 'overflow: hidden' on the (hidden) textarea used to compute
the (visible) textarea height ensures that there is no vertical
scrollbar, which would lead to a not so precise computation of the
height. The bug could be observed in sale.order form view, in the
order line x2many (description field), and had been introduced by
ef46378cd38d.
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo