Fixed #24084 - Changed HTMLSelectElement Index Signature

[irrationalRock]

This PR addresses microsoft/TypeScript#24084.

I changed the HTMLSelectElement index to [name: string]: HTMLOptionElement | HTMLOptGroupElement.

Thanks for considering this PR.

[saschanaz]

String indexers generally don't work, unless the target interface has no other members.

[mhegazy]

A string indexer type should be of a type that covers every property on the type.

[irrationalRock]

Thanks for the comments.

I changed the signature to [name: number]: HTMLOptionElement | HTMLOptGroupElement