anchor.diff:          var offset = readOffset();
           var expression = readExpression();
           int count = readUInt();
  -        List<SwitchCase> cases = new List<SwitchCase>(count);
  +        List<SwitchCase> cases =
  +            new List<SwitchCase>.filled(count, null, growable: true);
           for (int i = 0; i < count; ++i) {
             cases[i] = new SwitchCase.empty();
           }
  
positive.code: 
    List<Combinator> readCombinatorList() {
      int length = readUInt();
      List<Combinator> result = new List<Combinator>(length);
      for (int i = 0; i < length; ++i) {
        result[i] = readCombinator();
      }
  
negative.code: 
    List<Supertype> readSupertypeList() {
      int length = readUInt();
      List<Supertype> result =
          new List<Supertype>.filled(length, null, growable: true);
      for (int i = 0; i < length; ++i) {
        result[i] = readSupertype();
      }
  