function reloadDoc(doc) {

        var promise = FileUtils.readAsText(doc.file);

        promise.done(function (text, readTimestamp) {
            doc.refreshText(text, readTimestamp);
        });
        promise.fail(function (error) {
            console.log("Error reloading contents of " + doc.file.fullPath, error);
        });
        return promise;
    }
Reloads the Document's contents from disk, discarding any unsaved changes in the editor.

@param {!Document} doc
@return {$.Promise} Resolved after editor has been refreshed; rejected if unable to load the
     file's new content. Errors are logged but no UI is shown.