anchor.diff:  
     List<MapEntry> readMapEntryList() {
       int length = readUInt();
  -    List<MapEntry> result = new List<MapEntry>(length);
  +    List<MapEntry> result =
  +        new List<MapEntry>.filled(length, null, growable: true);
       for (int i = 0; i < length; ++i) {
         result[i] = readMapEntry();
       }
  
positive.code: 
    List<Expression> readExpressionList() {
      int length = readUInt();
      List<Expression> result = new List<Expression>(length);
      for (int i = 0; i < length; ++i) {
        result[i] = readExpression();
      }
  
negative.code: 
    List<String> readStringReferenceList() {
      int length = readUInt();
      List<String> result = new List<String>.filled(length, null, growable: true);
      for (int i = 0; i < length; ++i) {
        result[i] = readStringReference();
      }
  