anchor.diff:  
         String path = uriSource.fullName;
         File resource = _resourceProvider.getFile(path);
  -      Uri fileUri = _resourceProvider.pathContext.toUri(path);
         FileSource source = new FileSource(resource, uri);
  -      file = new FileState._(this, path, uri, fileUri, source);
  +      file = new FileState._(
  +          this, path, uri, _absolutePathToFileUri(path), source);
         _uriToFile[uri] = file;
         _addFileWithPath(path, file);
         file.refresh(allowCached: true);
  
positive.code:   FileSystemStateTestView _testView;
  
    FileSystemState(
        this._logger,
        this._byteStore,
        this._contentOverlay,
        this._resourceProvider,
        this._sourceFactory,
        this._analysisOptions,
        this._salt,
        {this.externalSummaries,
        this.parseExceptionHandler}) {
      _fileContentCache =
          _FileContentCache.getInstance(_resourceProvider, _contentOverlay);
      _testView = new FileSystemStateTestView(this);
  
negative.code:       fileStamp++;
      }
      files.add(file);
    }
  
    /**
     * A specialized version of package:path context.toUri(). This assumes the
     * path is absolute as does a performant conversion to a file: uri.
     */
    Uri _absolutePathToFileUri(String path) {
      if (path.contains(r'\')) {
        return new Uri(scheme: 'file', path: path.replaceAll(r'\', '/'));
      } else {
        return new Uri(scheme: 'file', path: path);
      }
    }
  }
  
  