Online mortgage banker MortgageIT.com is poised to become a top originator in the country after its merger with IPISkyscraper Inc., one of the nation’s largest mortgage brokers that spun MortgageIT off in 1999. The announcement came this week at a time when the fortunes of online mortgage lenders have been sinking and companies have been looking to combine the strengths of traditional brick-and-mortar operations with the benefit of Internet technology in order to survive.