[@babel/traverse]: Allowed node aliases as keys in visitors.

[cameron-martin]

This is made possible by babel/babel#9110.

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[typescript-bot]

@cameron-martin Thank you for submitting this PR!

🔔 @yortus @marvinhagemeister @rpetrich @mgroenhoff - please review this PR in the next few days. Be sure to explicitly select Approve or Request Changes in the GitHub UI so I know what's going on.

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[typescript-bot]

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