There’s no telling when life will serve you an ice-cream sundae, just because. By golly if Philip Rivers of San Diego wasn’t handed a triple-scooper with nuts and a cherry last week, when the Kansas City Chiefs traded cornerback Marcus Peters out of his neighborhood. The cagey Peters had become a royal nuisance to several NFL quarterbacks but especially Rivers. A year ago, in heading two victories that kept Rivers’ team out of the Super Bowl tournament, the cornerback filched three Rivers passes and got both hands on three others. Only 25, Peters loomed as an obstacle in seasons ahead to Rivers, 36, claiming an AFC West title, much less his first Super Bowl berth. Now, Peters is gone, shipped out of conference to the Los Angeles Rams. Goodness gracious, that makes it two apparent gifts to Rivers and mates this winter, from the same rival. Remember, the Chiefs agreed to send quarterback Alex Smith out of conference as well. The trades soon will become official. For a franchise that historically has fielded stiffs at quarterback, Smith led the NFL in passer rating last year, while also guiding K.C. to its second consecutive AFC West title and fourth playoff berth in his five seasons with K.C.