Kid stuff? Maybe. But How to Train Your Dragon, from the book by Cressida Cowell, works enough miracles of 3-D animation to charm your socks off. The story follows conventional lines: Viking teen Hiccup (voiced with sly comic skill by Jay Baruchel) is a wimpy misfit to his chief-dad, Stoick the Vast (Gerard Butler), and the babe-ish Astrid (America Ferrera). They want all dragons dead. After befriending the wounded beast Toothless, Hiccup wants to make peace, and Gobber (Craig Ferguson, hilarious), the village blacksmith, thinks he has a point. That’s it for plot. But writer-directors Chris Sanders and Dean DeBlois (Lilo & Stitch) make funny, touching, sublime entertainment out of it.