chat-fe: resuscitate scrollback
If the initial 20 messages doesn't cause the messages container to
overflow then the backlog will never be requested, making scrollback
impossible. This is due to making the container have position:relative
in order to display an overlay inside it.  Fixed by unconditionally
requesting the first page of backlog on load.
@@ -100,7 +100,7 @@ export class ChatScreen extends Component {
}
if (
- state.numPages * 100 >= props.length ||
+ (props.length >= 100 && state.numPages * 100 >= props.length) ||
this.hasAskedForMessages ||
props.length <= 0
) {
