anchor.diff:  
     Index(this._store);
   
  -  void deleteIndexForEntry(FileStatus status) {
  -    if (_statusIdx.containsKey(status.path)) {
  -      _statusIdx.remove(status.path);
  +  void deleteIndexForEntry(String path) {
  +    if (_statusIdx.containsKey(path)) {
  +      _statusIdx.remove(path);
       }
     }
   
  
positive.code:    * Walks over all the files in the working tree. Returns sha of the
     * working tree.
     */
     Future<String> walkFilesAndUpdateIndex(chrome.DirectoryEntry root) {
       List<String> filePaths = [];
       return FileOps.listFiles(root).then((List<chrome.ChromeFileEntry> entries) {
         if (entries.isEmpty) {
  
negative.code:            }
           }
        }).then((_) {
           return filePaths;
         });
      });
    }
  
  