/**
* Since wfMsg() and co suck, they don't return false if the message key they
* looked up didn't exist but a XHTML string, this function checks for the
- * nonexistance of messages by looking at wfMsg() output
+ * nonexistance of messages by checking the MessageCache::get() result directly.
*
* @param $key String: the message key looked up
* @return Boolean True if the message *doesn't* exist.