Set oven control to broil. Lightly spray cookie sheet with cooking spray. Place tomatoes and chiles on cookie sheet. Broil with tops 5 to 6 inches from heat 10 to 15 minutes, turning once or twice, until lightly charred and blistered. Place chiles in small bowl; set aside to cool. Place tomatoes in resealable food-storage plastic bag; seal bag and let stand 10 minutes.