Polyfill: Make Duration.p.with() conform to spec

The spec text uses ToTemporalPartialDurationRecord here, not
PrepareTemporalFields.

This is relevant because we are going to refactor PrepareTemporalFields as
part of #2925.

polyfill/lib/duration.mjs

@@ -160,23 +160,8 @@ export class Duration {
   }
   with(durationLike) {
     if (!ES.IsTemporalDuration(this)) throw new TypeError('invalid receiver');
-    const partialDuration = ES.PrepareTemporalFields(
-      durationLike,
-      [
-        'days',
-        'hours',
-        'microseconds',
-        'milliseconds',
-        'minutes',
-        'months',
-        'nanoseconds',
-        'seconds',
-        'weeks',
-        'years'
-      ],
-      'partial'
-    );
-    let {
+    const partialDuration = ES.ToTemporalPartialDurationRecord(durationLike);
+    const {
       years = GetSlot(this, YEARS),
       months = GetSlot(this, MONTHS),
       weeks = GetSlot(this, WEEKS),

polyfill/lib/ecmascript.mjs

@@ -229,16 +229,6 @@ const BUILTIN_CASTS = new Map([
   ['millisecond', ToIntegerWithTruncation],
   ['microsecond', ToIntegerWithTruncation],
   ['nanosecond', ToIntegerWithTruncation],
-  ['years', ToIntegerIfIntegral],
-  ['months', ToIntegerIfIntegral],
-  ['weeks', ToIntegerIfIntegral],
-  ['days', ToIntegerIfIntegral],
-  ['hours', ToIntegerIfIntegral],
-  ['minutes', ToIntegerIfIntegral],
-  ['seconds', ToIntegerIfIntegral],
-  ['milliseconds', ToIntegerIfIntegral],
-  ['microseconds', ToIntegerIfIntegral],
-  ['nanoseconds', ToIntegerIfIntegral],
   ['offset', ToPrimitiveAndRequireString]
 ]);