function assertResendCountdown(component, timeRemaining) {
  var el = component.getResendCountdown();
  var expected = 'Resend code in ' + timeRemaining;
  var actual = goog.dom.getTextContent(el);
  assertEquals(expected, actual);
}
Asserts the resend countdown indicates the given time remaining.
@param {!goog.ui.Component} component The PhoneSignInFinish component.
@param {number} timeRemaining The time remaining.