message: Use the Browser's ResizeObserver if it exists
  Instead of always using the ResizeObserver of the library, we instead
  polyfill the browser's one if it doesn't exist and use that then. On an
  up to date browser this removes the unnecessary polling that happens in
  the library's implementation.
diff: import * as React from "react";
  import { expect } from "../util/OptionUtil";
  -import { ResizeObserver } from "resize-observer";
  +import { install } from "resize-observer";
  import "../css/Abbreviated.scss";
  +if (!(window as any).ResizeObserver) { install(); }
  +
  export interface Props {
  abbreviations: string[],
  }
  @@ -23,9 +25,10 @@ export default class Abbreviated extends React.Component<Props> {
  public componentDidMount() {
  const element = expect(this.element.current, "Element should exist by now.");
  - new ResizeObserver(() => {
  + new (window as any).ResizeObserver(() => {
  this.chooseAbbreviation();
  }).observe(element);
  +
  this.chooseAbbreviation();
  }
  