function _docIsOutOfSync(doc) {
        var liveDoc = _server && _server.get(doc.file.fullPath),
            isLiveEditingEnabled = liveDoc && liveDoc.isLiveEditingEnabled();

        return doc.isDirty && !isLiveEditingEnabled;
    }
Documents are considered to be out-of-sync if they are dirty and
 do not have "update while editing" support
@param {Document} doc