anchor.diff:    }
   }
   
  -/// Adapter of [FileSystemState] to [FileSystem].
  -class _FileSystemAdaptor implements FileSystem {
  +/// Adapter of [FileSystemState] to [front_end.FileSystem].
  +class _FileSystemAdaptor implements front_end.FileSystem {
     final FileSystemState fsState;
     final pathos.Context pathContext;
   
     _FileSystemAdaptor(this.fsState, this.pathContext);
   
     @override
  -  FileSystemEntity entityForUri(Uri uri) {
  +  front_end.FileSystemEntity entityForUri(Uri uri) {
       if (uri.isScheme('file')) {
         var path = pathContext.fromUri(uri);
         var file = fsState.getFileForPath(path);
         return new _FileSystemEntityAdaptor(uri, file);
       } else {
  -      throw new ArgumentError(
  -          'Only file:// URIs are supported, but $uri is given.');
  -    }
  -  }
  -}
  -
  -/// Adapter of [FileState] to [FileSystemEntity].
  -class _FileSystemEntityAdaptor implements FileSystemEntity {
  +      throw new front_end.FileSystemException(
  +          uri, 'Only file:// URIs are supported, but $uri is given.');
  +    }
  +  }
  +}
  +
  +/// Adapter of [FileState] to [front_end.FileSystemEntity].
  +class _FileSystemEntityAdaptor implements front_end.FileSystemEntity {
     final Uri uri;
     final FileState file;
   
  
positive.code: class _AnalyzerKernelTarget extends KernelTarget {
    final Map<Uri, Map<Uri, List<CollectedResolution>>> resolutions = {};
  
    _AnalyzerKernelTarget(FileSystem fileSystem, DillTarget dillTarget,
        UriTranslator uriTranslator, MetadataCollector metadataCollector)
        : super(fileSystem, true, dillTarget, uriTranslator,
              metadataCollector: metadataCollector);
  
negative.code:   final PerformanceLog _logger;
  
    /// The [FileSystem] to access file during compilation.
    final front_end.FileSystem _fileSystem;
  
    /// The object that knows how to resolve "package:" and "dart:" URIs.
    final UriTranslator uriTranslator;
  