[css-fonts-4] Clarify definition of CSSFontFaceRule

[cdoublev]

I think this sentence is an oversight in CSSFontFaceRule definition:

The (now superseded) DOM Level 2 Style specification defined a different variant of this rule. This definition supersedes that one.

DOM Level 2 defines the exact same interface.

This commit defined CSSFontFaceRule descriptors as attributes with the above sentence. This commit removed the attributes but not the above sentence.

I do noy know how CSSFontFaceRule.style is supposed to work but this sentence could be replaced by an issue saying it is under consideration.

I guess it depends on #5649 but more recent at-rules seem to have been defined with descriptors as attributes, whereas #5649 resolved on defining different interfaces for declarations blocks that expose a different set of descriptors/properties.

[svgeesus]

Thanks for spotting. The sentence is indeed leftover from the time a different interface was in CSS Fonts 3, and then moved over to 4, before being deleted and replaced by the actually-implemented one from DOM 2.