message: Fix scroll-inview-parent to not check concrete type of HTMLElement.
  This should fix SSR.
diff: @@ -7,7 +7,7 @@ import { ScrollInviewContainer } from './container';
  export class AppScrollInviewParent extends Vue {
  // If this is a child of AppScrollScroller, we need to get it as a prop so
  // we can use that scroll element as the root context.
  - @Prop(propOptional(HTMLElement, null)) scroller!: null | HTMLElement;
  + @Prop(propOptional(Object, null)) scroller!: null | HTMLElement;
  // We need to create a new container for each unique "margin" that our
  // AppScrollInview children need. This is a map of margin => container.
  