message: Remove sanity check from requestAnimationFrame
  It should be in all major browsers as of years ago, and we use it unguarded elsewhere in the app. The performance benefits of it appear to be worthwhile enough to keep it, though it's not a perfect solution.
diff: @@ -115,20 +115,12 @@ export default class LeftPanel2 extends React.Component<IProps, IState> {
  };
  private handleStickyHeaders(list: HTMLDivElement) {
  - // TODO: Evaluate if this has any performance benefit or detriment.
  - // See https://github.com/vector-im/riot-web/issues/14035
  -
  if (this.isDoingStickyHeaders) return;
  this.isDoingStickyHeaders = true;
  - if (window.requestAnimationFrame) {
  window.requestAnimationFrame(() => {
  this.doStickyHeaders(list);
  this.isDoingStickyHeaders = false;
  });
  - } else {
  - this.doStickyHeaders(list);
  - this.isDoingStickyHeaders = false;
  - }
  }
  private doStickyHeaders(list: HTMLDivElement) {
  