GoDaddy.com, the leading registration company for Internet addresses, has agreed to take over and manage more than 850,000 domain names belonging to customers of a troubled rival, officials announced yesterday. The deal means that customers of that rival, RegisterFly.com, could once again renew names, or transfer them elsewhere if they do not want to stay with GoDaddy. Those names had been in limbo following financial and operational troubles at RegisterFly. The Internet Corporation for Assigned Names and Numbers, the organization in charge of the Internet's addressing policies, said the deal was good for RegisterFly customers.