Rollup merge of #117212 - clubby789:fix-ternary-recover, r=compiler-errors

Properly restore snapshot when failing to recover parsing ternary

If the recovery parsed an expression, then failed to eat a `:`, it would return `false` without restoring the snapshot. Fix this by always restoring the snapshot when returning `false`.

Draft for now because I'd like to try and improve this recovery further.

Fixes #117208

Author: matthiaskrgr