Editorial: Move special case out of ValidateTemporalRoundingIncrement

This moves the check for the special case (where dividend is 1 and
inclusive is false) out of ValidateTemporalRoundingIncrement, and into the
two call sites where it matters (PDT.p.round and ZDT.p.round). This will
hopefully make the logic in ValidateTemporalRoundingIncrement easier to
follow.

UPSTREAM_COMMIT=9bd27a20ef157c69d4d4954e64724eb332b32723

Author: ptomato

lib/ecmascript.ts

@@ -978,8 +978,7 @@ export function ToTemporalRoundingIncrement(options: { roundingIncrement?: numbe
   return MathTrunc(increment);
 }
 export function ValidateTemporalRoundingIncrement(increment: number, dividend: number, inclusive: boolean) {
-  let maximum = dividend;
-  if (!inclusive) maximum = dividend > 1 ? dividend - 1 : 1;
+  const maximum = inclusive ? dividend : dividend - 1;
   if (increment > maximum) {
     throw new RangeError(`roundingIncrement must be at least 1 and less than ${maximum}, not ${increment}`);
   }

lib/plaindatetime.ts

@@ -311,7 +311,9 @@ export class PlainDateTime implements Temporal.PlainDateTime {
       microsecond: 1000,
       nanosecond: 1000
     };
-    ES.ValidateTemporalRoundingIncrement(roundingIncrement, maximumIncrements[smallestUnit], false);
+    const maximum = maximumIncrements[smallestUnit];
+    const inclusive = maximum === 1;
+    ES.ValidateTemporalRoundingIncrement(roundingIncrement, maximum, inclusive);
 
     let year = GetSlot(this, ISO_YEAR);
     let month = GetSlot(this, ISO_MONTH);

lib/zoneddatetime.ts

@@ -353,7 +353,9 @@ export class ZonedDateTime implements Temporal.ZonedDateTime {
       microsecond: 1000,
       nanosecond: 1000
     };
-    ES.ValidateTemporalRoundingIncrement(roundingIncrement, maximumIncrements[smallestUnit], false);
+    const maximum = maximumIncrements[smallestUnit];
+    const inclusive = maximum === 1;
+    ES.ValidateTemporalRoundingIncrement(roundingIncrement, maximum, inclusive);
 
     // first, round the underlying DateTime fields
     const dt = dateTime(this);