[make determination of exp size handle new constructs properly
John Meacham <john@repetae.net>**20060815041925] hunk ./Grin/Simplify.hs 279
+sizeExp Let { expDefs = defs, expBody = body } = sizeExp body + sum (map (sizeLam . funcDefBody) defs)
+sizeExp MkCont { expCont = l1, expLam = l2 } = 1 + sizeLam l1 + sizeLam l2