Web GolfScript

# Canned test input:
;"Based off ETAOIN SHRDLU, your challenge is to write the shortest program or function in any language that outputs the 26 letters of the English alphabet based on their frequency in the input. Your program/function will receive as input a string of text, which will contain one or more uppercase and/or lowercase letters and may also contain punctuation, numerals, symbols, and other non-alphabetic characters. The program/function must output only the 26 UPPERCASE letters of the English alphabet, including those that do not appear in the input, ordered from most to least frequent based on how many times they appear in the input. The frequency is calculated case-insensitively, but the output must be in uppercase. If two or more letters have the same frequency, they may be in any order. No other output, such as whitespace, is allowed."

# Actual program code:
:?91,+-26>{.32+]?\-,}$