message: use arrayFastClone instead of slice
diff: @@ -38,6 +38,7 @@ import {haveTileForEvent} from "../views/rooms/EventTile";
  import {UIFeature} from "../../settings/UIFeature";
  import {objectHasDiff} from "../../utils/objects";
  import {replaceableComponent} from "../../utils/replaceableComponent";
  +import { arrayFastClone } from "../../utils/arrays";
  const PAGINATE_SIZE = 20;
  const INITIAL_SIZE = 20;
  @@ -1142,11 +1143,11 @@ class TimelinePanel extends React.Component {
  _getEvents() {
  const events = this._timelineWindow.getEvents();
  - // `slice` performs a shallow copy of the array
  + // `arrayFastClone` performs a shallow copy of the array
  // we want the last event to be decrypted first but displayed last
  // `reverse` is destructive and unfortunately mutates the "events" array
  - events
  - .slice().reverse()
  + arrayFastClone(events)
  + .reverse()
  .forEach(event => {
  if (event.shouldAttemptDecryption()) {
  event.attemptDecryption(MatrixClientPeg.get()._crypto);
  