title = async () => {
  validate();
  const result = await runtimeHandler.runtimeEvaluate("document.title");
  return result.result.value;
}
Returns page's title.
@example
await openBrowser();
@example
await goto("www.google.com");
@example
await title(); # returns "Google"

@returns {Promise<string>} - The title of the current page.