The Sherman Oaks Galleria, nationally recognized cradle of the Valley Girl, is all, like, closing. Like, totally going out of business. The cosmic bubble of gleaming escalators and 999,000 square feet of retail space was immortalized in the 1980s teen flicks “Valley Girl” and “Fast Times at Ridgemont High.” Now the mall is nearly deserted, a victim of the 1994 Northridge earthquake and its own failure to keep up with the times. Part of the problem, too, is that the Valley Girl is grown up: “Right now she’s 35 and about to be a senior partner in a downtown law firm. She’s morphed into something much more important,” says California historian Kevin Starr. On April 1 the Galleria will close for an extensive overhaul. It is scheduled to reopen in about two years, heavily reincarnated with office space but also featuring 18 movie theaters and an open-air ground floor of nothing but restaurants.