This fixes issues with CTRL+A then delete. Now CTRL+A selects all the contents of the unbreakable node in which the range is contained. Deleting it all will replace the contents with `<p><br></p>` so the user can start editing afresh. Note: Only CTRL+A is handled: ``select all`` in contextual and edit menus are still handled by the browser. closes odoo/odoo#30648