message: fix(Sticky): broke ssr
diff: import { isHidden } from '../utils/dom/style';
  -import { createNamespace, isDef } from '../utils';
  +import { createNamespace, isDef, isServer } from '../utils';
  import { getScrollTop, getElementTop, getScroller } from '../utils/dom/scroll';
  import { BindEventMixin } from '../mixins/bind-event';
  @@ -65,7 +65,7 @@ export default createComponent({
  created() {
  // compatibility: https://caniuse.com/#feat=intersectionobserver
  - if (window.IntersectionObserver) {
  + if (!isServer && window.IntersectionObserver) {
  this.observer = new IntersectionObserver(
  entries => {
  // trigger scroll when visibility changed
  