The loaded event should only fire when we've actually triggered a refresh. If loaded is bound when the iframe is created, sometimes the blank iframe will fire a 'load' event before a refresh is triggered (this occurred with relative frequency in firefox). By binding the loaded event in the refresh function, we prevent this from occurring.
git-svn-id: https://develop.svn.wordpress.org/trunk@20049 602fd350-edb4-49c9-b593-d223f7449a82
