These fields have no label associated to them. While it's more or less
obvious for sighted users that these fields are associated with the
table cell next to them, visually impaired users might not get that
association when using the screen reader in forms mode.
Note we're using `aria-label` instead of `aria-labelledby`. IMHO in this
case `aria-labelledby` is the superior method because it guarantees the
text is present for both sighted and visually impaired users. However,
testing for fields with no label other than the one provided by
`aria-labelledby` is hard since Capybara has no support for this
attribute.
So we're using `aria-label` and testing the presence of the text on the
page (with the `within "tr", text:` statements) as well as the ARIA
label (with the `fill_in` statements).