anchor.diff:    }
   
     T _parse<T>(
  -      String source, void parseFunction(Parser parser, Token previousToken)) {
  +      String source, void parseFunction(Parser parser, Token previousToken),
  +      {bool inAsync: false, bool inCatchBlock: false}) {
       ScannerResult scan = scanString(source);
   
       return CompilerContext.runWithOptions(options, (CompilerContext c) {
  
positive.code:   Expression parseExpression(String source,
        {List<ErrorCode> codes,
        List<ExpectedError> errors,
        int expectedEndOffset}) {
      // TODO(brianwilkerson) Check error codes.
      return _parse(source, (parser, token) => parser.parseExpression(token));
    }
  
    @override
  
negative.code: import '../../generated/parser_test.dart';
  import '../../generated/test_support.dart';
  
  /// Implementation of [AbstractParserTestCase] specialized for testing building
  /// Analyzer AST using the fasta [Forest] API.
  class FastaBodyBuilderTestCase extends Object
      with ParserTestHelpers
      implements AbstractParserTestCase {
  