fix: css codesplit inline problem

[sanyuan0704]

Description

fixes #5348

Additional context

Css code is gone after build when using ?inline and dynamic import. It can reproduce in https://github.com/lovetingyuan/bug-vite-dymamic-import-css.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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