code: function _renameItem(oldPath, newPath, newName, isFolder) {
          var result = new $.Deferred();
  
          if (oldPath === newPath) {
              result.resolve();
          } else if (!isValidFilename(newName)) {
              result.reject(ERROR_INVALID_FILENAME);
          } else {
              var entry = isFolder ? FileSystem.getDirectoryForPath(oldPath) : FileSystem.getFileForPath(oldPath);
              entry.rename(newPath, function (err) {
                  if (err) {
                      result.reject(err);
                  } else {
                      result.resolve();
                  }
              });
          }
  
          return result.promise();
      }
docs: Rename a file/folder. This will update the project tree data structures
  and send notifications about the rename.
  
  @param {string} oldPath Old name of the item with the path
  @param {string} newPath New name of the item with the path
  @param {string} newName New name of the item
  @param {boolean} isFolder True if item is a folder; False if it is a file.
  @return {$.Promise} A promise object that will be resolved or rejected when
  the rename is finished.