A precocious kid born into a showbiz family, Lily Allen ignored haters, bucked convention, and built a steady following for her breezy music online. By the time Alright, Still came out, even skeptics couldn’t resist her sly send-ups of London youth culture and her crafty eviscerations of would-be boyfriends. Whether she’s sizing up street scenes in “LDN” or stumbling through a packed club on “Friday Night,” Allen’s voice, clever lyrics, and sunny fusion of ska, dance pop, and hip-hop are exhilarating and infectious.