_**Robin Williams as a 10 year-old; great cast, but needed a rewrite**_ The Powells in Oakland have a premature baby, whom they name Jack (Robin Williams). The problem is that Jack grows at four times the normal rate and so when he finally is allowed to enter 5th grade at the age of 10 he looks like a 40 year-old man. Diane Lane plays his mother, Bill Cosby his tutor, Jennifer Lopez his teacher and Fran Drescher a single mother who’s attracted to him. “Jack” (1996) takes the basic topic of “Big” (1988) and mixes it with the awkwardness of “Milk Money” (1994). It tries to be a serious drama,…