anchor.diff:  
     accept(ConstantVisitor visitor) => visitor.visitType(this);
   
  -  String toString() => 'TypeConstant(${Error.safeToString(representedType)})';
  +  String toString() => 'TypeConstant(${representedType})';
   }
   
   class ListConstant extends ObjectConstant {
  
positive.code:     sb.write('MapConstant({');
      for (int i = 0 ; i < keys.entries.length ; i++) {
        if (i > 0) sb.write(',');
        sb.write(Error.safeToString(keys.entries[i]));
        sb.write(':');
        sb.write(Error.safeToString(values[i]));
      }
      sb.write('})');
      return sb.toString();
  
negative.code:     int i = 0;
      fieldElements.forEach((Element field, Constant value) {
        if (i > 0) sb.write(',');
        sb.write(field.name);
        sb.write('=');
        sb.write(value);
        i++;
      });
      sb.write('))');
  