RFR: 8372203: Piecewise linear easing function [v4]

[Michael Strauß]

On Wed, 26 Nov 2025 22:36:14 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> I've noticed that the text in cssref.html says "two or more", not "one or more". I'm going to change that.
>
> Thanks. That's why I asked whether < 2 should be IAE. Fixing the cssref is good.

I'm going to correct myself once more. It seems like this has changed between spec revisions, and per the [final spec](https://www.w3.org/TR/css-easing-2/#linear-easing-function-parsing), even though the syntax uses the "one or more" modifier, the parsing algorithm adds the following restriction:

> If there are less than two [items](https://infra.spec.whatwg.org/#list-item) in stopList, then return failure.

So I'm going to change that again, and add an appropriate IAE if length < 2.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1977#discussion_r2566653570