Auto merge of #17858 - emilio:hover-quirk-broken, r=canaltinova
Auto merge of #17858 - emilio:hover-quirk-broken, r=canaltinova

selectors: Fix note_next_sequence.

Selector-matching can backtrack when looking for ancestor combinators, so we
can't just arrive there once and forget.

Also, there was a further problem before this patch, which was that
note_next_sequence was called _before_ checking whether all simple selectors
matched, so the sequence you could get there is just wrong.

Bug: 1384020
Reviewed-by: canaltinova
MozReview-Commit-ID: 6g0ibb8EfBU

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