Philadelphia’s Morgan Frost, right, scores against Washington goaltender Clay Stevenson (33) during an NHL preseason game in Washington last September. Stevenson, the former Dartmouth College goalie, was called up to the Capitals on Monday from their AHL affiliate, the Hershey Bears, for whom he has posted a 2.94 goals against average, a .888 save percentage, two shutouts and a 18-5-5 record this season. The Capitals — who have been without their No. 1 netminder, Logan Thompson, the last two weeks due to an upper-body injury — were to visit the N.Y. Islander on Tuesday night before closing the regular-season schedule at Pittsburgh on Thursday evening.