EventTarget constructor が使えないときに無理矢理 EventTarget クラスを作るコード。

MyEventTarget.js

class MyEventTarget extends DocumentFragment {
  constructor() {
    super();
    Object.setPrototypeOf(this, EventTarget.prototype);
  }

  static [Symbol.hasInstance](instance) {
    return instance instanceof EventTarget;
  }
}

const source = `
for (const key of Object.getOwnPropertyNames(self)) {
  const target = self[key];
  if (!(target instanceof Function)) { continue; }
  if (target.prototype == null) { continue; }
  if (!(target.prototype instanceof EventTarget)) { continue; }

  try {
    new target();
    console.log(key);
  } catch {}
}
`;
const blob = new Blob([source], { type: "text/javascript" });
const url = URL.createObjectURL(blob);
new Worker(url);

Worker 内だと FileReader かな。

Feature Detection 付きの新しい方。
https://gist.github.com/petamoriken/d3745051d6f7684af58985d18efa2786