message: Only update analytics when there's a change
  Also, the arguments are the previous state, not the new state.
diff: @@ -86,8 +86,10 @@ const LeftPanel = React.createClass({
  return false;
  },
  - componentDidUpdate(newProps, newState) {
  - Analytics.setBreadcrumbs(newState.breadcrumbs);
  + componentDidUpdate(prevProps, prevState) {
  + if (prevState.breadcrumbs !== this.state.breadcrumbs) {
  + Analytics.setBreadcrumbs(this.state.breadcrumbs);
  + }
  },
  _onBreadcrumbsChanged: function(settingName, roomId, level, valueAtLevel, value) {
  