tools: enable no-return-await lint rule

Enable lint rule that prohibits unnecessary use of `await` with
`return`.

PR-URL: #17265
Reviewed-By: Timothy Gu <[email protected]>
Reviewed-By: Vse Mozhet Byt <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Anatoli Papirovski <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>

.eslintrc.yaml

@@ -69,6 +69,7 @@ rules:
       message: __defineGetter__ is deprecated.
     - property: __defineSetter__
       message: __defineSetter__ is deprecated.
+  no-return-await: error
   no-self-assign: error
   no-throw-literal: error
   no-unused-labels: error