FP NaN are not comparable (e.g. nan != nan)

### Describe the bug

Floating-point values that are NaN are not comparable. So all tests should check if computed.isNan equals expected.isNaN before checking if computed == expected.

### To Reproduce

Create two NaN values and compare them. They should not be equal even if their bitfields are.

### Expected behavior

_No response_

### Actual behavior

_No response_

### Additional: Dart SDK info

_No response_

### Additional: pubspec.yaml

```yaml

```

### Additional: Context

_No response_