[CssSelector] Fix :nth-last-child() translation
merged branch lazyhammer/issue-8068-2.1 (PR #8073)

This PR was merged into the 2.1 branch.

Discussion
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[CssSelector] Fix :nth-last-child() translation

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #8068
| License       | MIT
| Doc PR        | n/a

Same as #8072, but for < 2.3

Commits
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1469953 [CssSelector] Fix :nth-last-child() translation