function assertEmailLinkSignInLinkingPage(opt_email, opt_providerName) {
  assertPage_(container, 'firebaseui-id-page-email-link-sign-in-linking');
  if (opt_email) {
    assertPageContainsText(opt_email);
  }
  if (opt_providerName) {
    assertPageContainsText(opt_providerName);
  }
}
Asserts that the email link sign in linking page is rendered.
@param {string=} opt_email Optional email to check.
@param {string=} opt_providerName Optional provider name to check.