L.S. Dunes don’t sound like a supergroup, and they certainly don’t want to be called a supergroup. But when they took to the Rise Stage early on a Friday afternoon to effectively kick off Riot Fest, one could be forgiven for mistaking them for that. While other stages saw audiences in the dozens under the midday Chicago sun, the debuting quintet amassed thousands of onlookers. As vocalist Anthony Green pointed out from the stage, it was a bigger crowd than just about any other band would have for their first show (including all of his so far), but that’s to be expected when the Circa Survive/Saosin/The Sound of Animals Fighting frontman joined forces with guitarists Frank Iero (My Chemical Romance) and Travis Stever (Coheed and Cambria) and the rhythm section from Thursday (drummer Tucker ...