anchor.diff:        srcPath = library.path;
       } else {
         String libraryPath = library.path;
  -      int index =
  -          libraryPath.lastIndexOf(resourceProvider.pathContext.separator);
  +      int index = libraryPath.lastIndexOf(separator);
         if (index == -1) {
           index = libraryPath.lastIndexOf('/');
           if (index == -1) {
  
positive.code:   String getRelativePathFromFile(File file) {
      String filePath = file.path;
      String libPath = libraryDirectory.path;
      if (!filePath
          .startsWith("$libPath${resourceProvider.pathContext.separator}")) {
        return null;
      }
      return filePath.substring(libPath.length + 1);
  
negative.code:       String prefix = libraryPath.substring(0, index + 1);
        srcPath = '$prefix$relativePath';
      }
      String filePath = srcPath.replaceAll('/', separator);
      try {
        File file = resourceProvider.getFile(filePath);
        return file.createSource(parseUriWithException(dartUri));
  