The anti-fascists are wearing their sweatpants today. Tennis shoes are a must. They’ve been told to wear something breathable — no masks, no bandanas, no armor. Almost nobody wears black (almost nobody). Gym members drift in through the door of the Breakaway Social Center in the Little Village neighborhood on Chicago’s West Side. The two-story corner building was once home to a $10-a-haircut barbershop, but now the walls are lined with posters bearing anarchist symbols and advertising a recent lecture on militant suffragettes. The couches are pushed back to the walls, next to shelves stacked with political journals. On the...