[sobject] fix notification operation
regression introduced in bf4003760e02 Operation use self. session. not self._cw.
I'm a bit surprised that its not tested.
closes ##2870077
/*
* cubicweb js mock for unit tests
* This module defines variables and functions used in quite a few places
* in cw js framework that can't be used or guessed without a real CW server
*/
var pageid = 'my-page-id';
function _(message) {
return message;
}