Bug 1061421 - [Contacts] Delete all contacts which were set to ICE, 'ICEcontacts' list is empty but the whole ICE section should be removed r=sergi

I think it would be better to structure it like this:
```js
ICEContacts.updateICEContacts().then(function() {
  sinon.assert.calledWith(MockLazyLoader.load, [iceContactsOverlay]);
  done();
});
```
It's just less crufty.