I couldn't get it to work (with random web pages) in Safari.
Trying to paste it to the URL bar gives the error: "Safari doesn’t allow JavaScript from the Smart Search Field. To allow this, choose “Allow JavaScript from Smart Search Field” from the Develop menu."
But even after enabling that option, it still doesn't work. Javascript console shows the errors:
[Error] Refused to load http://kathack.com/js/kh.js because it does not appear in the script-src directive of the Content Security Policy.
[Error] Refused to load http://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js because it does not appear in the script-src directive of the Content Security Policy.