Re: [csswg-drafts] [scroll-animations] Ignore unknown descriptors (#5109)

> We should allow (but ignore if unknown) _any_ descriptor, otherwise it's a problem for **forwards compat**.

Do forwards-compat requires that ignored properties should be exposed in CSSOM? Related:  #2736.

Browsers seems to interpret these wordings differently:

```html
<style>
  @page { /* "The @page rule can only contain page properties"... */
    top: 1px; /* ... `top` is not one of them */
  }
  @keyframes animation {
    from { /* "The <declaration-list> inside of <keyframe-block> accepts any CSS property except those defined in this specification" */
      animation-name: 'foo';
    }
  }
</style>
<script>
const { styleSheets: [{ cssRules: [{ style: pageStyle }, { cssRules: [{ style: keyframeStyle }] }] }] } = document

console.log(keyframeStyle.animationName) // Chrome: 'foo' | Firefox: ''
console.log(pageStyle.top) // Chrome: '1px' | Firefox: ''
</script>
```

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Received on Tuesday, 28 June 2022 04:41:15 UTC