getRandomSymbol is slightly biased

[danstiner]

Currently symbols are chosen from an alphabet by just modding a uin32 down to the length of the alphabet, this can introduce bias for non-power-of-two alphabet sizes of about 2^-32 - 2^-log2(|alphabet|) or about 1/2^21 for a wordlist with about two thousand words. This is small but not entirely negligible and should be fixed.

password-generator/javascripts/crypto_random_generator.js

Line 35 in f700e6a

symbol: alphabet[randomValues[0] % alphabet.length],

Relevant reference: https://stackoverflow.com/questions/137783/expand-a-random-range-from-1-5-to-1-7