anchor.diff:        String path = uriSource.fullName;
         File resource = _resourceProvider.getFile(path);
         FileSource source = new FileSource(resource, uri);
  -      file = new FileState._(
  -          this, path, uri, _absolutePathToFileUri(path), source);
  +      file = new FileState._(this, path, uri, source);
         _uriToFile[uri] = file;
         _addFileWithPath(path, file);
         file.refresh(allowCached: true);
  
positive.code:   final Uri uri;
  
    /**
     * The absolute file URI of the file.
     */
    final Uri fileUri;
  
    /**
     * The [Source] of the file with the [uri].
     */
    final Source source;
  
negative.code:    */
    bool hasErrorOrWarning = false;
  
    FileState._(this._fsState, this.path, this.uri, this.source)
        : isInExternalSummaries = false;
  
    FileState._external(this._fsState, this.uri)
        : isInExternalSummaries = true,
          path = null,
          source = null,
          _exists = true {
      _apiSignature = new Uint8List(16);
  