anchor.diff:        List<String> errors) {
       _buildUnit = unit;
       _buildRoot = _buildUnit.buildRoot;
  -    if (!_buildRoot.endsWith('/')) {
  -      _buildRoot = '$_buildRoot/';
  +    if (!_buildRoot.endsWith(separator)) {
  +      _buildRoot = '$_buildRoot${separator}';
       }
   
       var jsTree = _emitModule(compilationUnits);
  
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:     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;
  