tests/dict_fromkeys: Revert to use reversed() to run in native codegen mode.

tests/basics/dict_fromkeys.py

@@ -9,6 +9,6 @@ l.sort()
 print(l)
 
 # argument to fromkeys has no __len__
-#d = dict.fromkeys(reversed(range(1)))
-d = dict.fromkeys((x for x in range(1)))
+d = dict.fromkeys(reversed(range(1)))
+#d = dict.fromkeys((x for x in range(1)))
 print(d)