Fix type of `zero?' to properly handle 0.0.

original commit: 7ece2a4872bfd02d7b62b39c040e877c7ba638ee

collects/tests/typed-scheme/unit-tests/typecheck-tests.rkt

@@ -807,6 +807,7 @@
                 (vector-ref #("a" "b") (sub1 x))
                 (vector-ref #("a" "b") (- x 1)))
               -String]
+        [tc-err (string-append "bar" (if (zero? (ann 0.0 Float)) #f "foo"))]
         )
   (test-suite
    "check-type tests"

collects/typed-scheme/private/base-env-numeric.rkt

@@ -41,7 +41,8 @@
   )
 
 ;; numeric predicates
-[zero? (make-pred-ty (list N) B -Zero)]
+[zero? (asym-pred N B (-FS (-filter (Un -Flonum -Zero) 0)
+                           (-not-filter -Zero 0)))]
 [number? (make-pred-ty N)]
 [integer? (asym-pred Univ B (-FS (-filter (Un -Integer -Flonum) 0)
 				     (-not-filter -Integer 0)))]