Text/plain form payloads have entries separated by a \r\n newline, but the HTML specification (https://html.spec.whatwg.org/#plain-text-form-data) requires there to be a final \r\n newline, which WebKit skips.
(ignore the "formdata event" tests, since those are meant to test entries added to the form entry list through the formdata event, which WebKit doesn't yet implement)
Created attachment 444180 [details]
Created attachment 444207 [details]
Created attachment 444292 [details]
Committed r286221 (244602@main): <https://commits.webkit.org/244602@main>
All reviewed patches have been landed. Closing bug and clearing flags on attachment 444292 [details].