✨ `@supported` shorthand for whether declarations are supported

[Aron]

Description

Case 1

- grid@supports(display:grid)
+ grid@supported

@supports (display:grid) {
    .grid\@supported {
        display: grid
    }
}

Case 2

- {grid;w:100dvw}@supports(display:grid)and(width:100dvw)
+ {grid;w:100dvw}@supported

@supports (display:grid) and (width:100dvw) {
    .\{grid\;w\:100dvw\}\@supported {
        display: grid;
        width: 100dvw;
    }
}