RFR: 8345188: Support tree-structural pseudo-classes [v6]

[John Hendrikx]

On Wed, 8 Jan 2025 21:31:50 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> I think we do need to mention the old selector in the CSS Ref because it is still supported.
>> 
>> We should also tell the developers what they need to do with the existing stylesheets, whether to update them to use the new selector, or, if we plan to support the old one indefinitely, explain that.
>
> Maybe we should deprecate the non-standard `.root` class and mention that in the cssref?

I only pointed this out as I didn't see removal of the old `.root` code, in which case it should either still be documented or mentioned that it will be removed in the future.  I can go with either solution.

-------------

PR Review Comment: https://git.openjdk.org/jfx/pull/1652#discussion_r1907922889