Cornflakes is not the same thing as "flaked corn".
Flaked corn is whole grain corn that's been pre-geletinized and run through a roller. Cornflakes (Kellogg's or otherwise) are a processed food that uses milled corn as its primary ingredient, but certainly is not the brewing equivalent of flaked corn. You don't really want those preservatives in your wort.
Ingredients for flaked corn:
Corn - flaked
Ingredients for Cornflakes:
Milled Corn
Sugar
Malt flavoring
High fructose corn syrup
Salt
Iron
Niacinamide
Sodium ascorbate and ascorbic acid (vitamin C)
Pyridoxine hydrochloride (vitamin B6)
Riboflavin (vitamin B2)
Thiamin hydrochloride (vitamin B1)
Vitamin A palmitate
Folic acid
Vitamin B12
Vitamin D
Vitamin B