Summary: nsIDOMFileError.idl (http://mxr.mozilla.org/mozilla1.9.2/source/content/base/public/nsIDOMFileError.idl) contains all the correct error codes except for ABORT_ERR, which currently is value 25 but should be value 20 according to the specification.
Current Behavior: ABORT_ERR is 25
Expected Behavior: The Working Draft covering FileError is: http://www.w3.org/TR/2009/WD-FileAPI-20091117/#dfn-fileerror . ABORT_ERR is 20
Fixed as part of bug 530901