RFR: 8314820: Unify Screen adapter ordinal logic

[Andy Goryachev]

On Tue, 16 Dec 2025 12:42:05 GMT, Marius Hanl <mhanl at openjdk.org> wrote:

> This is a small improvement that was noted back in https://github.com/openjdk/jfx/pull/1200#issuecomment-1671954361 by @mstr2, and was on my list since then.
> 
> The idea is to have only one place for assigning `adapter ordinals` – within `Screen`. The corresponding setter `setAdapterOrdinal` can therefore be made private. This improves the separation of responsibilities a little. :-)

One thought nagged me during the review: why do we keep the ordinal (an index) when we could, in theory, keep a reference to the object?  Is there a potential for misalignment, perhaps a transient one?

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PR Comment: https://git.openjdk.org/jfx/pull/2009#issuecomment-3661497743