CHINESE people above the age of 30 may recall their happy child-hood days playing with crudely made building blocks, slingshots andrag dolls. Lego sets have since replaced building blocks, as tanks,racing cars and toy guns have supplanted the humble slingshot. Bar-bie Dolls with complete wardrobes and cuddly cartoon charactertoys have also rendered the rag doll a museum piece. Children’s tastes in toys, incommon with all other aspects of Chinese life, have moved with the times.