Add a validation for `FrozenArray<dictionary>`

[saschanaz]

Highly possible that it won't do what it intended to do. See: whatwg/webidl#1243, w3c/mediasession#343

Using FrozenArray<dictionary> would:

1. Convert each dictionary to JS object
2. Make an array with them and freeze the array
3. Now the attribute returns cached array with JS objects which is not frozen