[css-inline-3] Clarification on text-box-trim propagation and independent block formatting contexts

There was a related issue at https://github.com/w3c/csswg-drafts/issues/11038 but I couldn't quite identift whether this specific question about text-box-trim was resolved.

CSS Inline 3 says the below regarding text-box-trim, which doesn't seem to include specific behavior for independent BFCs. I don't see anything else about propagation in this property definition (other than column containers).

Note: Like ::first-line, this property does not apply to, or propagate through, flex, grid, or table formatting contexts.

CSS Pseudo 4 does say the following about the first formatted line, though.

Note: The first line of a block container that does not itself participate in a block formatting context cannot be the first formatted line of an ancestor element.

I'm not 100% sure, but I think the "does not itself participate in a block formatting context" is synonymous with "establishes an independent block formatting context"? Does this definition mean that text-box-trim does not propagate through independent BFCs?

That's my interpretation, but there's an existing WPT that asserts the opposite - new-fc-001.html passes if text-box-trim does propagate to an independent BFC (a display: flow-root in this case). Blink passes that, Gecko and WebKit do not. I was going to add additional tests to assert that propagation doesn't happen with other BFC-establishing children, but this existing WPT has me a bit perplexed.

(Tracking this on the Gecko side at https://bugzilla.mozilla.org/show_bug.cgi?id=2049484)

Read the CSS Inline 3 text-box-trim definition and the CSS Pseudo 4 first-formatted-line wording, then compare them with the related issue 11038. Run or inspect the WPT case css/css-inline/text-box-trim/new-fc-001.html and review the linked Gecko bug. Done means the propagation behavior for independent BFCs is resolved in the specification and the test expectation is aligned.