Normative: change ordering of balancing operations in Temporal.Durati…

…on.prototype.round

If we balance the bigger units before the smaller ones, then we never
properly balance the days that are added from balancing units up to day
length. Changing the order of operations ensures proper balancing of all
units.
There is also no more need for the call to MoveRelativeZonedDateTime()
in the end of the method, so it's been removed.

Closes: #2508

UPSTREAM_COMMIT=36746e5ef8da4688237c195e51c8081e3304ab0f

lib/duration.ts

@@ -308,10 +308,6 @@ export class Duration implements Temporal.Duration {
         roundingMode,
         relativeTo
       ));
-    ({ years, months, weeks, days } = ES.BalanceDurationRelative(years, months, weeks, days, largestUnit, relativeTo));
-    if (ES.IsTemporalZonedDateTime(relativeTo)) {
-      relativeTo = ES.MoveRelativeZonedDateTime(relativeTo, years, months, weeks, 0);
-    }
     ({ days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds } = ES.BalanceDuration(
       days,
       hours,
@@ -323,6 +319,7 @@ export class Duration implements Temporal.Duration {
       largestUnit,
       relativeTo
     ));
+    ({ years, months, weeks, days } = ES.BalanceDurationRelative(years, months, weeks, days, largestUnit, relativeTo));
 
     return new Duration(years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds);
   }