fix: avoid DOM Clobbering gadget in getRelativeUrlFromDocument

[jackfromeast]

Description

This patch fixes the DOM Clobbering gadget in the getRelativeUrlFromDocument function.

Reference: GHSA-64vr-g452-qvp3

[stackblitz]

Run & review this pull request in StackBlitz Codeflow.

[patak-dev]

/ecosystem-ci run

[vite-ecosystem-ci]

📝 Ran ecosystem CI on 84b30b3: Open

suite	result	latest scheduled
histoire	❌ failure	❌ failure
nuxt	❌ failure	✅ success
remix	❌ failure	❌ failure
sveltekit	✅ success	❌ failure
vike	❌ failure	❌ failure

✅ analogjs, astro, ladle, laravel, marko, previewjs, quasar, qwik, rakkas, redwoodjs, storybook, unocss, vite-environment-examples, vite-plugin-pwa, vite-plugin-react, vite-plugin-react-swc, vite-plugin-svelte, vite-plugin-vue, vite-setup-catalogue, vitepress, vitest, vuepress

[vite-ecosystem-ci]

📝 Ran ecosystem CI on 84b30b3: Open

suite	result	latest scheduled
histoire	❌ failure	❌ failure
remix	❌ failure	❌ failure
sveltekit	✅ success	❌ failure
vike	❌ failure	❌ failure

✅ analogjs, astro, ladle, laravel, marko, nuxt, previewjs, quasar, qwik, rakkas, redwoodjs, storybook, unocss, vite-environment-examples, vite-plugin-pwa, vite-plugin-react, vite-plugin-react-swc, vite-plugin-svelte, vite-plugin-vue, vite-setup-catalogue, vitepress, vitest, vuepress

[patak-dev]

Thanks @jackfromeast!