What happened to convertEntities?

I was using the javascript function convertEntities in a plugin that worked great until recently and now the function seems to have vanished under 3.3 – Is there a substitute function I should be using?

I am tempted to just copy the function into my script – is there a reason that is a bad idea?

convertEntities was removed because strings are passed to JavaScript via json_encode() now:

http://core.trac.wordpress.org/ticket/11520