Method constructor

lib/utils/test/mockResizeObserver.ts:78–82

(callback: ResizeObserverCallback)

  #elements: Set<HTMLElement> = new Set();

  constructor(callback: ResizeObserverCallback) {
    this.#callback = callback;

    emitter.addListener("change", this.#onChange);
  }

  observe(element: HTMLElement) {
    if (this.#disconnected) {