Littler is a grammatically incorrect word that is used by too many Americans and especially by females. When a speaker uses the word littler in a sentence, such as "That boy is littler than the other" it makes the speaker sound like a completely uneducated nimrod. The correct wording would be small or smaller. See Nutt-Racket post from 'Jenna the Great' to see such intelligence.
I heard a girl say this word and I thought it sounded completely uneducated. Her brain must be littler than mine. See Nutt-Racket