fix: preserve the separator between selectors when an unused selector is in between

[navorite]

fixes #13945

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[changeset-bot]

🦋 Changeset detected

Latest commit: 392ba82

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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svelte	Patch

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[pkg-pr-new]

pnpm add https://pkg.pr.new/svelte@13954

commit: 392ba82

[dummdidumm]

thank you!