message: frontend: MultiFirehose improvements
  Use this.resources instead of this.props.resources, so that
  MultiFirehose doesn't modify its own props.
  Also fix nulling out the firehose attribute on unmount.
diff: @@ -87,26 +87,24 @@ Firehose.propTypes = {
  export class MultiFirehose extends FirehoseBase {
  constructor(props) {
  super(props);
  - this.props.resources.forEach((resource) => {
  - resource.firehose = this._initFirehose(resource);
  - });
  + this.resources = props.resources.map(r => Object.assign({}, r, {firehose: this._initFirehose(r)}));
  }
  componentDidMount() {
  - this.props.resources.forEach((resource) => {
  + this.resources.forEach((resource) => {
  this._mountFirehose(resource.firehose, resource);
  });
  }
  componentWillUnmount() {
  - this.props.resources.forEach((resource, index) => {
  + this.resources.forEach((resource, i) => {
  this._unmountFirehose(resource.firehose);
  - resource.firehose[index] = null;
  + this.resources[i].firehose = null;
  });
  }
  render() {
  - const reduxes = this.props.resources.map((resource) => {
  + const reduxes = this.resources.map((resource) => {
  return _.defaults({}, { reduxID: resource.firehose.id }, resource);
  });
  