Editorial?: Use normalized time duration in operations

This introduces Normalized Time Duration Records, which we use to
encapsulate 96-bit integer operations on duration times. (In the reference
polyfill, the TimeDuration class fulfills the same purpose.) These
operations are specified naively in the mathematical value domain, but can
be changed in a later editorial commit to correspond to how
implementations would write 64+32 bit operations, if we so desire. (The
results must be exactly the same, so that can be decided later, outside of
a TC39 plenary.)

This commit also replaces TotalDurationNanoseconds with
NormalizeTimeDuration, and NanosecondsToDays with
NormalizedTimeDurationToDays. Several operations are changed to return a
Normalized Duration Record, which is a Normalized Time Duration record
combined with a Date Duration Record.

Having already limited time units of durations in the previous commit,
this does not affect any results, nor any existing tests in test262. But I
can't prove conclusively that there isn't some edge case somewhere that
makes this change observable.

(also obsoletes several pre-existing editorial mistakes)
Closes: #2536
Closes: #2638
Closes: #2616

polyfill/lib/calendar.mjs

@@ -22,6 +22,7 @@ import {
   HasSlot,
   SetSlot
 } from './slots.mjs';
+import { TimeDuration } from './timeduration.mjs';
 
 const ArrayFrom = Array.from;
 const ArrayIncludes = Array.prototype.includes;
@@ -157,16 +158,15 @@ export class Calendar {
     duration = ES.ToTemporalDuration(duration);
     options = ES.GetOptionsObject(options);
     const overflow = ES.ToTemporalOverflow(options);
-    const { days } = ES.BalanceTimeDuration(
-      GetSlot(duration, DAYS),
+    const norm = TimeDuration.normalize(
       GetSlot(duration, HOURS),
       GetSlot(duration, MINUTES),
       GetSlot(duration, SECONDS),
       GetSlot(duration, MILLISECONDS),
       GetSlot(duration, MICROSECONDS),
-      GetSlot(duration, NANOSECONDS),
-      'day'
+      GetSlot(duration, NANOSECONDS)
     );
+    const days = GetSlot(duration, DAYS) + ES.BalanceTimeDuration(norm, 'day').days;
     const id = GetSlot(this, CALENDAR_ID);
     return impl[id].dateAdd(
       date,