function getUserAgentDetected(agent) {
  switch (agent) {
    case UserAgents.GECKO:
      return userAgent.GECKO;
    case UserAgents.IE:
      return userAgent.IE;
    case UserAgents.WEBKIT:
      return userAgent.WEBKIT;
  }
  return null;
}
Return whether a given user agent has been detected.
@param {number} agent Value in UserAgents.
@return {boolean} Whether the user agent has been detected.
@suppress {checkTypes} suppression added to enable type checking