feat: add hasUnscopedGlobalCss to compile metadata

[paoloricciuti]

Closes #15449

From my tests it should be basically it (it's missing the --global keyframes but i'm gonna add them now) but please try to break it.

No test because we don't have a test suite for the compiled output...should we add it?

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🦋 Changeset detected

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-svelte-15450-svelte.vercel.app/

[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@15450

[Rich-Harris]

This feels very specific to vite-plugin-svelte, and given that zimmerframe is already in the dependency graph for anyone using it, the cost of doing the work inside vite-plugin-svelte feels very small, especially with the .includes(':global') check.

Given that, do we really want to add it here? It adds more code to svelte than vite-plugin-svelte would be able to remove, and the 'other tools' argument feels a bit hypothetical.

If the answer is 'yes' then I'd at least suggest changing the API so that it's result.css?.hasGlobal rather than adding metadata.

[paoloricciuti]

If the answer is 'yes' then I'd at least suggest changing the API so that it's result.css?.hasGlobal rather than adding metadata

Initially I added it there but it felt a bit wrong since we already have the metadata object. But if we want to move it it's fine too.

For the question of "should we do it" this could save one walk since we are already walking to analyze css but effectively does feels a bit specific.

At the end of the day the PR it's here, up to discuss if we want to do it, otherwise we can close it 😌