GetIntrinsic: remove from PlainDate, add monkeypatching test

.gitignore

@@ -5,3 +5,4 @@ tsc-out/
 .vscode/*
 !.vscode/launch.json
 *.tgz
+.DS_Store

lib/calendar.ts

@@ -1,6 +1,5 @@
 import { DEBUG } from './debug';
 import * as ES from './ecmascript';
-import { GetIntrinsic, MakeIntrinsicClass, DefineIntrinsic } from './intrinsicclass';
 import {
   CALENDAR_ID,
   ISO_YEAR,
@@ -28,6 +27,7 @@ import type {
   CalendarReturn as Return,
   FieldRecord
 } from './internaltypes';
+import { Duration } from './duration';
 
 const ArrayIncludes = Array.prototype.includes;
 const ArrayPrototypePush = Array.prototype.push;
@@ -244,7 +244,6 @@ export class Calendar implements Temporal.Calendar {
       'day'
     );
     const { years, months, weeks, days } = impl[GetSlot(this, CALENDAR_ID)].dateUntil(one, two, largestUnit);
-    const Duration = GetIntrinsic('%Temporal.Duration%');
     return new Duration(years, months, weeks, days, 0, 0, 0, 0, 0, 0);
   }
   year(dateParam: Params['year'][0]): Return['year'] {
@@ -344,9 +343,6 @@ export class Calendar implements Temporal.Calendar {
   [Symbol.toStringTag]!: 'Temporal.Calendar';
 }
 
-MakeIntrinsicClass(Calendar, 'Temporal.Calendar');
-DefineIntrinsic('Temporal.Calendar.from', Calendar.from);
-
 /**
  * Implementation for the ISO 8601 calendar. This is the only calendar that's
  * guaranteed to be supported by all ECMAScript implementations, including those

lib/duration.ts

@@ -1,6 +1,5 @@
 import { DEBUG } from './debug';
 import * as ES from './ecmascript';
-import { MakeIntrinsicClass } from './intrinsicclass';
 import {
   YEARS,
   MONTHS,
@@ -452,5 +451,3 @@ export class Duration implements Temporal.Duration {
   }
   [Symbol.toStringTag]!: 'Temporal.Duration';
 }
-
-MakeIntrinsicClass(Duration, 'Temporal.Duration');