Dunkin’ is phasing out its once-ubiquitous foam coffee cups. The shift is beginning in New England, where the cups will be jettisoned as of Dec. 1, with a full transition expected by April. The white, pink and orange foam cups conduct heat easily, and regular drinkers have protected their hands by “double-cupping” their coffee. Now, double-walled paper cups will become standard across the chain’s more than 9,000 U.S. stores amid rising concerns about the environment and state bans on Styrofoam.