Editorial: fix IteratorClose call in %IteratorHelperPrototype%.return

spec.html

@@ -46608,7 +46608,7 @@ <h1>%IteratorHelperPrototype%.return ( )</h1>
             1. If _O_.[[GeneratorState]] is ~suspended-start~, then
               1. Set _O_.[[GeneratorState]] to ~completed~.
               1. NOTE: Once a generator enters the completed state it never leaves it and its associated execution context is never resumed. Any execution state associated with _O_ can be discarded at this point.
-              1. Perform ? IteratorClose(_O_.[[UnderlyingIterator]], ReturnCompletion(*undefined*)).
+              1. Perform ? IteratorClose(_O_.[[UnderlyingIterator]], NormalCompletion(~unused~)).
               1. Return CreateIteratorResultObject(*undefined*, *true*).
             1. Let _C_ be ReturnCompletion(*undefined*).
             1. Return ? GeneratorResumeAbrupt(_O_, _C_, *"Iterator Helper"*).