message: Record exact scroll position for feed.
  Fixes:
diff: @@ -55,6 +55,7 @@ export class AppActivityFeed extends Vue {
  // the same feed we can scroll to the previous position that way.
  private scroll!: number;
  private scroll$: Subscription | undefined;
  + private scrollSampled$: Subscription | undefined;
  readonly number = number;
  @@ -74,9 +75,14 @@ export class AppActivityFeed extends Vue {
  emitLoadMore() {}
  mounted() {
  - this.scroll$ = Scroll.watcher.changes.sampleTime(ScrollSampleTime).subscribe(() => {
  + this.scroll$ = Scroll.watcher.changes.subscribe(() => {
  + // We use the scroll top directly, instead of going through scroll
  + // watcher, so that we can keep this as fast as possible.
  + this.scroll = Scroll.getScrollTop();
  + });
  +
  + this.scrollSampled$ = Scroll.watcher.changes.sampleTime(ScrollSampleTime).subscribe(() => {
  const { top, height } = Scroll.watcher.getScrollChange();
  - this.scroll = top;
  // Auto-loading while scrolling.
  if (this.feed.shouldScrollLoadMore) {
  @@ -98,6 +104,11 @@ export class AppActivityFeed extends Vue {
  this.scroll$.unsubscribe();
  this.scroll$ = undefined;
  }
  +
  + if (this.scrollSampled$) {
  + this.scrollSampled$.unsubscribe();
  + this.scrollSampled$ = undefined;
  + }
  }
  // TODO: This shouldn't be needed anymore, since we always show placholder
  