George Floyd’s death has raised new questions about a potentially dangerous method of restraint: the knee-to-neck maneuver.Floyd, a 46-year-old black man, was held down with a knee as he protested that he couldn’t breathe. The FBI is investigating the incident, which drew widespread condemnation of the officers, who were fired this week, after a video showing part of the encounter circulated on social media.The knee-to-neck