[css-sizing] Should `contain-intrinsic-*: from-element` require `contain:size`?

[kojiishi]

The from-element keyword is for "Auto-resize iframes based on content" #1771 based on the resolution in 2021.

When it applies only to <iframe>, which has little with contain:size, should it require contain:size to be effective?

/cc @tabatkins @chrishtr @bfgeek

[Loirooriol]

If anything, isn't from-element kinda bypassing size containment? Should it maybe require the opposite, that there isn't size containment? But then contain-intrinsic-* is probably not the right place for this