message: Abort scroll updates when already unmounted
  This checks whether we're unmounted before updating scroll state, as we use
  async functions and timeouts in this area.
  Fixes
diff: @@ -677,6 +677,11 @@ module.exports = createReactClass({
  debuglog("updateHeight getting straight to business, no scrolling going on.");
  }
  + // We might have unmounted since the timer finished, so abort if so.
  + if (this.unmounted) {
  + return;
  + }
  +
  const sn = this._getScrollNode();
  const itemlist = this.refs.itemlist;
  const contentHeight = this._getMessagesHeight();
  