anchor.diff:    /// during the round trip.
     final int offset;
   
  -  RoundTripFailure(this.uri, this.offset);
  +  TextSerializationVerificationFailure(this.uri, this.offset);
   }
   
  -class RoundTripSerializationFailure extends RoundTripFailure {
  +class TextSerializationFailure extends TextSerializationVerificationFailure {
     final String message;
   
  -  RoundTripSerializationFailure(this.message, Uri uri, int offset)
  +  TextSerializationFailure(this.message, Uri uri, int offset)
         : super(uri, offset);
   }
   
  -class RoundTripDeserializationFailure extends RoundTripFailure {
  +class TextDeserializationFailure extends TextSerializationVerificationFailure {
     final String message;
   
  -  RoundTripDeserializationFailure(this.message, Uri uri, int offset)
  +  TextDeserializationFailure(this.message, Uri uri, int offset)
         : super(uri, offset);
   }
   
  -class RoundTripMismatchFailure extends RoundTripFailure {
  +class TextRoundTripFailure extends TextSerializationVerificationFailure {
     final String initial;
     final String serialized;
   
  -  RoundTripMismatchFailure(this.initial, this.serialized, Uri uri, int offset)
  +  TextRoundTripFailure(this.initial, this.serialized, Uri uri, int offset)
         : super(uri, offset);
   }
   
   class TextSerializationVerifier implements Visitor<void> {
     /// List of errors produced during round trips on the visited nodes.
  -  final List<RoundTripFailure> failures = <RoundTripFailure>[];
  +  final List<TextSerializationVerificationFailure> failures =
  +      <TextSerializationVerificationFailure>[];
   
     Uri lastSeenUri = noUri;
   
  
positive.code:         writeNode(deserialized, expressionSerializer, uri, offset);
  
      if (initial != serialized) {
        failures
            .add(new RoundTripMismatchFailure(initial, serialized, uri, offset));
      }
    }
  
  
negative.code:         writeNode(deserialized, dartTypeSerializer, uri, offset);
  
      if (initial != serialized) {
        failures.add(new TextRoundTripFailure(initial, serialized, uri, offset));
      }
    }
  
  