HOLLYWOOD — There was some serious girl power going on Saturday afternoon at the Grove for the world premiere of “Kit Kittredge: An American Girl.”Throngs of girls, with their Kit dolls in tow, filled two theaters and later partied in the adjacent American Girl store, which shuttered for the fete. Preemgoers were urged to shop during the party, with proceeds benefiting the Children Affected by AIDS Foundation. Twelve-year-old Abigail Breslin, who said she had all the American Girl dolls prior to getting the part, admitted she needed to learn how to use a typewriter to play the role of journalist Kit Kittredge. “At first I asked them, ‘Where’s the (computer) screen?,’ ” she said. Event was bittersweet for the crew at Picturehouse, which Warner Bros. is in the process of shuttering. Bob Berney and Marian Koltai-Levine boldly made the premiere and party rounds. The entire Smith family (Will, Jada Pinkett, Trey, Jaden) showed up in support of moppet Willow Smith. Also attending: helmer Patricia Rozema; thesps Julia Ormond, Chris O’Donnell and Glenne Headly; and HBO’s Colin Callender.