plt/racket — pull request #719 by gus-massa (2014-07-08 02:14:26+00:00)
Title: optimizer: transform (if v x v) to (if v x #f)

A few changes in the beginning of optimize_branc

Add (if v x v) => (if v x #f)

and in test position, swap the order of
(if v v x) => (if v #t x)
and
(if v #t #f) => v