add: flavourSet.appendFlavour("application/x-moz-file", "nsIFile"); 
context:   getSupportedFlavours: function ()    {      var flavourSet = new FlavourSet();      flavourSet.appendFlavour("application/x-moz-file", "nsIFile");      flavourSet.appendFlavour("text/x-moz-url");      flavourSet.appendFlavour("text/unicode");      return flavourSet;    },
meta: 5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5872/0443141b5684b0a8da6fa88aa4ad857bc2d5dfb5/contentAreaDD.js/buggy/suite/common/contentAreaDD.js