code: function _doRevert(doc, suppressError) {
          var result = new $.Deferred();
  
          FileUtils.readAsText(doc.file)
              .done(function (text, readTimestamp) {
                  doc.refreshText(text, readTimestamp);
                  result.resolve();
              })
              .fail(function (error) {
                  if (suppressError) {
                      result.resolve();
                  } else {
                      showFileOpenError(error, doc.file.fullPath)
                          .done(function () {
                              result.reject(error);
                          });
                  }
              });
  
          return result.promise();
      }
docs: Reverts the Document to the current contents of its file on disk. Discards any unsaved changes
  in the Document.
  @private
  @param {Document} doc
  @param {boolean=} suppressError If true, then a failure to read the file will be ignored and the
  resulting promise will be resolved rather than rejected.
  @return {$.Promise} a Promise that's resolved when done, or (if suppressError is false)
  rejected with a FileSystemError if the file cannot be read (after showing an error
  dialog to the user).