message: used classnames module
diff: @@ -161,7 +161,8 @@ module.exports = createReactClass({
  const joinRules = this.props.room && this.props.room.currentState.getStateEvents("m.room.join_rules", "");
  const joinRule = joinRules && joinRules.getContent().join_rule;
  - const joinRuleClass = "mx_RoomHeader_PrivateIcon" + (joinRule === "invite" ? " mx_RoomHeader_isPrivate" : "");
  + const joinRuleClass = classNames("mx_RoomHeader_PrivateIcon",
  + {"mx_RoomHeader_isPrivate": joinRule === "invite"});
  if (this.props.onCancelClick) {
  cancelButton = <CancelButton onClick={this.props.onCancelClick} />;
  