[w3c/IndexedDB] error in an example of the behavior of in-line keys and key generators (Issue #443)

chairmank created an issue (w3c/IndexedDB#443)

I am reporting a possible error in the 28 February 2025 draft of the [Indexed Database API 3.0](https://www.w3.org/TR/IndexedDB-3/).

This is a quote from [Example 6](https://www.w3.org/TR/2025/WD-IndexedDB-3-20250228/#example-inline-keygen), regarding the behavior of in-line keys and key generators:

> Attempting to store a property on a primitive value will fail and throw an error. In the first example below the [key path](https://www.w3.org/TR/2025/WD-IndexedDB-3-20250228/#object-store-key-path) for the object store is "foo". The actual object is a primitive with the value, 4. Trying to define a property on that primitive value fails. The same is true for arrays. Properties are not allowed on an array. In the second example below, the actual object is an array, [10]. Trying to define a property on the array fails.
> 
> ```
> const store = db.createObjectStore("store", { keyPath: "foo", autoIncrement: true });
> 
> // The key generation will attempt to create and store the key path
> // property on this primitive.
> store.put(4); // will throw DataError
> 
> // The key generation will attempt to create and store the key path
> // property on this array.
> store.put([10]); // will throw DataError
> ```

When I test this behavior with recent releases of Chrome and Firefox, I observe that `store.put(4)` throws `DataError` as specified, but `store.put([10])` does not.

I think that the implementations are correct, and the specification is wrong. The following statement

> The same is true for arrays. Properties are not allowed on an array. 

in the specification is not true, as one can demonstrate in the browser's JavaScript console:

```
let array = [10]; // undefined
typeof array; //"object"
array['foo'] = 1; // 1
array['foo']; // 1
```

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