[fix] transform links to be absolute to avoid console error when navigating

[Rich-Harris]

fixes #3748. This doesn't have a test because I haven't been able to observe this behaviour with anything other than a <link rel="icon"> (and in any browser other than Chrome), and favicons are loaded somewhat unpredictably. (actually, we can test that link hrefs are absolute)

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[Rich-Harris]

absolutely bewildered by these safari failures

[benmccann]

a begrudging approval 😄 I hate that we have to do this, but it seems like the best course of action

[Rich-Harris]

wow. per 91049b7, this change really is responsible for those persistent failures. what the actual fucking hell, safari

[Rich-Harris]

ok, so it turns out that changing certain link hrefs causes scrolling to go batshit in safari. it turns out that if we only update link[rel=icon] everything works fine, and since the chrome bug only relates to those links, we should be fine. man, browsers are a mess

[benmccann]

@Magkoooh please don't approve already merged PRs as it just creates spam for the maintainers