anchor.diff:      // Sanity check embedder libs.
       var source = context.sourceFactory.forUri('dart:foobar');
       expect(source, isNotNull);
  -    expect(
  -        source.fullName,
  -        '/my/proj/sdk_ext/entry.dart'
  -            .replaceAll('/', io.Platform.pathSeparator));
  +    expect(source.fullName, '/my/proj/sdk_ext/entry.dart');
     }
   
     test_error_filter_analysis_option() async {
  
positive.code:     // Sanity check embedder libs.
      var source = context.sourceFactory.forUri('dart:foobar');
      expect(source, isNotNull);
      expect(
          source.fullName,
          '/my/proj/sdk_ext/entry.dart'
              .replaceAll('/', io.Platform.pathSeparator));
    }
  
    test_embedder_options() async {
  
negative.code:     var context = contexts[0];
      var source = context.sourceFactory.forUri('dart:foobar');
      expect(source, isNotNull);
      expect(source.fullName, '/my/proj/sdk_ext/entry.dart');
      // We can't find dart:core because we didn't list it in our
      // embedded_libs map.
      expect(context.sourceFactory.forUri('dart:core'), isNull);
  