CSS in @supports blocks is removed if compiling with cascade: false

[leereamsnyder]

(Realized I never made an issue to go with #1200)

with the cascade: false option, CSS in @supports blocks is getting removed

Here's a REPL: https://svelte.technology/repl?version=1.56.2&gist=e546039fc8c9aede35b4bff161016682

<div class='maybe-grid'>something with a nice layout</div>

<style>
  @supports (display: grid) {
    .maybe-grid {
      display: grid;
    }
  }
</style>

You would expect to get the code within the block e.g.

@supports (display: grid) {.maybe-grid[svelte-xyz]{display:grid}}

but you currently get

@supports (display: grid) {}

I have an attempt at a fix in #1200 . I made the probably naive assumption that @supports blocks should be treated in a similar fashion to @media

[Rich-Harris]

Thanks! I think treating it similarly to @media probably makes sense. Released 1.56.4 with the fix