message: Change CSS class for message panel spinner
  to stop scrollbars appearing when we
  - jump to a message or,
  - permalink that is to an not paginated in event
diff: @@ -1121,7 +1121,7 @@ var TimelinePanel = React.createClass({
  // exist.
  if (this.state.timelineLoading) {
  return (
  - <div className={this.props.className + " mx_RoomView_messageListWrapper"}>
  + <div className="mx_RoomView_messagePanelSpinner">
  <Loader />
  </div>
  );
  