[FIX] mail: add a max limit for chatter

- Task: https://www.odoo.com/web#id=6729&view_type=form&model=project.task&action=333&active_id=131
- Pad: https://pad.odoo.com/p/r.q6QePBp6BFlNfBEg
This is not correct actually. This methods works as follow : 

 - either you receive ids
 - either you receive a domain

I think you try to hack the method to make your thing work.