Can we eliminate this? It's just for test code, and the test code can reach in to Meteor.server directly. Eg:

```
Meteor.onConnection(function (serverConnection) {
  Meteor.server.sessions[serverConnection.id]._disableHeartbeat = disable;
});

Meteor.onConnect
```

I know it's abstraction breaking to reach in like that, but I think its better than adding an undocumented `_internal` field in a user-visible object.