anchor.diff:        subTest.lines[lineIndex] = line;
         int commentIndex = prefix.indexOf('// ');
         if (commentIndex != -1) {
  -        subTest.expectedError = prefix.substring(commentIndex + 3).trim();
  +        String combinedErrors = prefix.substring(commentIndex + 3);
  +        for (String error in combinedErrors.split(',')) {
  +          subTest.expectedErrors.add(error.trim());
  +        }
         }
         commonLines.add('');
       } else {
  
positive.code:       entryPoint: entryPoint,
        memorySourceFiles: sources,
        diagnosticHandler: collector);
    Expect.isFalse(result.isSuccess, "Expected compile time error for\n$subTest");
    Expect.equals(
        1, collector.errors.length, "Expected compile time error for\n$subTest");
    Expect.equals(
        'MessageKind.${subTest.expectedError}',
        collector.errors.first.messageKind.toString(),
        "Unexpected compile time error for\n$subTest");
  }
  
  class SubTest {
    String expectedError;
    final Map<int, String> lines = <int, String>{};
  
    String generateCode(List<String> commonLines) {
  
negative.code:       '54',
      ]);
  
      await runTest(
          'tests/dart2js_2/native/native_test.dart', 'tests/dart2js_2/native/', {
        'Class': Kind.regular,
        'NativeClass': Kind.native,
        'topLevelField': Kind.regular,
  