Port normative changes from tc39/proposal-temporal.

This ports over
tc39/proposal-temporal@f270527
tc39/proposal-temporal@0421e37

Author: 12wrigja

lib/init.js

@@ -6,6 +6,12 @@ if (module.parent && module.parent.id === 'internal/preload') {
 import('./index.mjs')
   .then(({ Temporal, Intl, toTemporalInstant }) => {
     globalThis.Temporal = { ...Temporal };
+    Object.defineProperty(globalThis.Temporal, Symbol.toStringTag, {
+      value: 'Temporal',
+      writable: false,
+      enumerable: false,
+      configurable: true
+    });
     Object.assign(globalThis.Intl, Intl);
     Object.defineProperty(Date.prototype, 'toTemporalInstant', {
       value: toTemporalInstant,

lib/now.mjs

@@ -49,3 +49,9 @@ export const Now = {
   zonedDateTime,
   zonedDateTimeISO
 };
+Object.defineProperty(Now, Symbol.toStringTag, {
+  value: 'Temporal.Now',
+  writable: false,
+  enumerable: false,
+  configurable: true
+});

test/now.mjs

@@ -29,6 +29,7 @@ describe('Temporal.Now', () => {
     it('Temporal.Now.timeZone is a function', () => equal(typeof Temporal.Now.timeZone, 'function'));
     it('Temporal.Now.zonedDateTimeISO is a function', () => equal(typeof Temporal.Now.zonedDateTimeISO, 'function'));
     it('Temporal.Now.zonedDateTime is a function', () => equal(typeof Temporal.Now.zonedDateTime, 'function'));
+    it('Temporal.Now has a toStringTag', () => equal(Temporal.Now.toString(), '[object Temporal.Now]'));
   });
   describe('Temporal.Now.instant()', () => {
     it('Temporal.Now.instant() returns an Instant', () => assert(Temporal.Now.instant() instanceof Temporal.Instant));