message: Monitoring: MonitoringUI no longer needs to extend SafetyFirst
  We don't use this.isMounted_ now, so SafetyFirst isn't needed.
diff: @@ -880,10 +880,8 @@ const CreateSilence = () => {
  : <SilenceForm defaults={{matchers}} saveButtonText="Create" title="Silence Alert" />;
  };
  -export class MonitoringUI extends SafetyFirst<null, null> {
  +export class MonitoringUI extends React.Component<null, null> {
  componentDidMount () {
  - super.componentDidMount();
  -
  const poll = (url: string, key: string, dataHandler: (data: any[]) => any): void => {
  store.dispatch(UIActions.monitoringLoading(key));
  const poller = (): void => {
  @@ -954,7 +952,6 @@ export class MonitoringUI extends SafetyFirst<null, null> {
  }
  componentWillUnmount () {
  - super.componentWillUnmount();
  _.each(pollerTimeouts, t => clearTimeout(t));
  }
  