anchor.diff:      show PackageBundleAssembler;
   import 'package:analyzer/src/task/strong/info.dart' show DynamicInvoke;
   import 'package:source_maps/source_maps.dart';
  +import 'package:path/path.dart' show separator;
   
   import '../closure/closure_annotator.dart' show ClosureAnnotator;
   import '../js_ast/js_ast.dart' as JS;
  
positive.code:     // TODO(vsm): This is not unique if an escaped '/'appears in a filename.
      // E.g., "foo/bar.dart" and "foo$47bar.dart" would collide.
      qualifiedPath = uri.pathSegments.skip(1).join(separator);
    } else if (uri.path.startsWith(buildRoot)) {
      qualifiedPath =
          uri.path.substring(buildRoot.length).replaceAll('/', separator);
    } else {
      // We don't have a unique name.
      throw 'Invalid build root.  $buildRoot does not contain ${uri.path}';
    }
    return pathToJSIdentifier(qualifiedPath);
  }
  
negative.code:       List<String> errors) {
      _buildUnit = unit;
      _buildRoot = _buildUnit.buildRoot;
      if (!_buildRoot.endsWith(separator)) {
        _buildRoot = '$_buildRoot${separator}';
      }
  
      var jsTree = _emitModule(compilationUnits);
  