function requestViaAnchor(url, additionalAttributes) {
  return requestViaNavigable(
      "a",
      Object.assign({"href": url, "innerHTML": "Link to resource"},
                    additionalAttributes),
      document.body, a => a.click());
}
Creates a new anchor element, appends it to {@code document.body} and
    performs the navigation.
@param {string} url The URL to navigate to.
@return {Promise} The promise for success/error events.