currentURL = async () => {
  validate();
  const locationObj = await runtimeHandler.runtimeEvaluate(
    "window.location.toString()",
  );
  return locationObj.result.value;
}
Returns window's current URL.
@example
await openBrowser();
@example
await goto("www.google.com");
@example
await currentURL(); # returns "https://www.google.com/?gws_rd=ssl"

@returns {Promise<string>} - The URL of the current window.