Due to the declaration of the CurzIndex variable as a global one, this code is not equivalent to the preexistent one when there is more than one instance of navigationStack object (see https://github.com/mozilla-b2g/gaia/blob/master/apps/communications/contacts/js/contacts.js#L13 and https://github.com/mozilla-b2g/gaia/blob/master/apps/communications/contacts/js/views/settings.js#L96).

I guess the intention of this new variable was to simplify and to accelerate this evaluation |var zIndex = this.stack[this.stack.length - 1].zIndex + 1;| Is that right, @AshayNeema ? Although I would be in favor of that improvement (properly implemented, of course), sadly it is not the focus of this bug and I would recommend file a new bug to deal with it separately. So to say it, the update to navigation.js included in this PR is not needed for the new multiple contact deletion functionality and the original version of navigation.js would perfectly deal with it.