Editorial: Remove errant [[Duration]] reference from RoundRelativeDur…

…ation

The `duration` value is already an Internal Duration Record, which is the
type returned by RoundRelativeDuration (which does not have an internal
slot of [[Duration]] anyhow).

spec/plainyearmonth.html

@@ -615,7 +615,7 @@ <h1>
           1. Let _isoDateTime_ be CombineISODateAndTimeRecord(_thisDate_, MidnightTimeRecord()).
           1. Let _isoDateTimeOther_ be CombineISODateAndTimeRecord(_otherDate_, MidnightTimeRecord()).
           1. Let _destEpochNs_ be GetUTCEpochNanoseconds(_isoDateTimeOther_).
-          1. Set _duration_ to ? RoundRelativeDuration(_duration_, _destEpochNs_, _isoDateTime_, ~unset~, _calendar_, _settings_.[[LargestUnit]], _settings_.[[RoundingIncrement]], _settings_.[[SmallestUnit]], _settings_.[[RoundingMode]]).[[Duration]].
+          1. Set _duration_ to ? RoundRelativeDuration(_duration_, _destEpochNs_, _isoDateTime_, ~unset~, _calendar_, _settings_.[[LargestUnit]], _settings_.[[RoundingIncrement]], _settings_.[[SmallestUnit]], _settings_.[[RoundingMode]]).
         1. Let _result_ be ? TemporalDurationFromInternal(_duration_, ~day~).
         1. If _operation_ is ~since~, set _result_ to CreateNegatedTemporalDuration(_result_).
         1. Return _result_.