formatRangeToParts produces an empty source when FormatApproximately is used

[trflynn89]

If Intl.NumberFormat.prototype.formatRangeToParts is provided approximately equivalent values, PartitionNumberRangePattern will return early by way of FormatApproximately. However, FormatApproximately does not set the [[Source]] internal slot for the approximatelySign or any of the partitions in the result vector. FormatNumericRangeToParts then blindly adds a source property to the object it returns.

In our implementation over at SerenityOS's LibJS, this currently results in an empty string:

> new Intl.NumberFormat().formatRangeToParts(1, 1)
[
    { "type": "approximatelySign", "value": "~", "source": "" },
    { "type": "integer", "value": "1", "source": "" }
]

Should [[Source]] be set (maybe to "shared") in FormatApproximately?

[sffc]

Yes it should. Duplicate of #63

[trflynn89]

Oops! Looked through the open issues and missed that one, thanks!