mouseevent.path for safari and firefox.js

if (!('path' in Event.prototype)) {
  Object.defineProperty(Event.prototype, 'path', {
    get: function () {
      const path = [];
      let currentElem = this.target;
      while (currentElem) {
        path.push(currentElem);
        currentElem = currentElem.parentElement;
      }
      if (path.indexOf(window) === -1 && path.indexOf(document) === -1)
        path.push(document);
      if (path.indexOf(window) === -1)
        path.push(window);
      return path;
    }
  });
}