CSS.supports("grid-template-areas", `""`)
CSS.supports("grid-template-areas", `"" ""`)

They are both true in Firefox and false in Chromium and old Edge. Looking at https://drafts.csswg.org/css-grid/#propdef-grid-template-areas,

• There is no trash token.
• All strings have the same number of columns (0).
• There's in no non-rectangular named grid area (since there's no named grid area).

So it seems valid per the spec. But also pretty pointless, so possibly it was not deliberate. Given that neither Chromium nor old Edge support that, should we really allow it?