Correctly parse lists of enums in Dart generated code (#7157)

* Correctly parse lists of enums in Dart generated code

* Add a test for #6869

* Commit generated code

* Fixed missing newline-at-eof

tests/DartTest.sh

@@ -25,6 +25,8 @@ cp monster_test.fbs ../dart/test
 
 cd ../dart
 
+../flatc --dart --gen-object-api -o ./test ./test/list_of_enums.fbs
+
 # update packages
 dart pub get
 # Execute the sample.

tests/monster_test_my_game.example_generated.dart

@@ -152,7 +152,7 @@ class _LongEnumReader extends fb.Reader<LongEnum> {
   const _LongEnumReader();
 
   @override
-  int get size => 1;
+  int get size => 8;
 
   @override
   LongEnum read(fb.BufferContext bc, int offset) =>