For a little kid, a wait in a long line can seem endless – tragic, even, to one boy who’d thrown himself on the ground Friday morning and begun to whimper softly. Becca Mangan, 18, strove to keep things lively for her daughter, Charlie, as they waited outside the Christmas Bureau. Besides taking Charlie, 1, to play in the snow – scraped into lumpy piles on the wet grass – she employed a variety of tactics: walking, running in circles, pointing out cars and clouds.