operator== only checks the generic type

Current implementation of operator== checks the generic type instead of the parameterized type. For example:

```dart
class Tuple2 {
@override
bool operator ==(other) =>
other is Tuple2 &&
other.item1 == item1 &&
other.item2 == item2;
```

What is the reason for not checking the parameterized type?

```dart
other is Tuple2
```