[FIX] web: Dashboards error
[FIX] web: Dashboards error

Steps to reproduce:
Go to any pivot view (for example Sales > Report > Sales) and add
the current view to your personnal dashboard (in the search view: Favourites > Add to my Dashboard)
Go to the dashboard, traceback because $buttons was not defined.

opw:707296

Elico-Corp/odoo_OCB,bplancher/odoo,bplancher/odoo,hip-odoo/odoo,dfang/odoo,ygol/odoo,ygol/odoo,Elico-Corp/odoo_OCB,dfang/odoo,ygol/odoo,laslabs/odoo,laslabs/odoo,dfang/odoo,dfang/odoo,ygol/odoo,laslabs/odoo,bplancher/odoo,ygol/odoo,laslabs/odoo,hip-odoo/odoo,bplancher/odoo,laslabs/odoo,hip-odoo/odoo,bplancher/odoo,Elico-Corp/odoo_OCB,Elico-Corp/odoo_OCB,hip-odoo/odoo,hip-odoo/odoo,hip-odoo/odoo,dfang/odoo,ygol/odoo,Elico-Corp/odoo_OCB,bplancher/odoo,dfang/odoo,Elico-Corp/odoo_OCB,ygol/odoo,laslabs/odoo