anchor.diff:          createListener(builder, memberScope, builder.isInstanceMember);
   
       if (!isTopLevel) {
  -      Token classToken = scanString('class Cx {}').tokens;
         listener.classDeclaration = astFactory.classDeclaration(
           null,
           null,
           null,
  -        classToken,
  -        astFactory.simpleIdentifier(classToken.next),
  +        new Token(Keyword.CLASS, 0),
  +        astFactory.simpleIdentifier(
  +            new StringToken.fromString(TokenType.IDENTIFIER, 'Cx', 6)),
           null,
           null,
           null,
  
positive.code: 
  import 'package:front_end/src/fasta/parser.dart' show MemberKind, Parser;
  
  import 'package:front_end/src/scanner/token.dart' show Token;
  
  import 'package:front_end/src/fasta/source/source_library_builder.dart'
      show SourceLibraryBuilder;
  
negative.code: 
  import 'package:front_end/src/fasta/kernel/body_builder.dart' show BodyBuilder;
  
  import 'package:front_end/src/fasta/type_inference/type_inference_engine.dart'
      show TypeInferenceEngine;
  
  