message: fix: make _handleScroll function compatible with ie11
  On Internet Explorer 11 the `path` is undefined
  Closes:
diff: @@ -216,7 +216,7 @@ export class NgDropdownPanelComponent implements OnInit, OnChanges, OnDestroy {
  .pipe(takeUntil(this._destroy$), auditTime(0, SCROLL_SCHEDULER))
  .subscribe((e: { path, composedPath, target }) => {
  const path = e.path || (e.composedPath && e.composedPath());
  - const scrollTop = path.length === 0 ? e.target.scrollTop : path[0].scrollTop
  + const scrollTop = !path || path.length === 0 ? e.target.scrollTop : path[0].scrollTop
  this._onContentScrolled(scrollTop);
  });
  });
  