feat(@formatjs/intl-locale): update impl to match stage-3

also fix #4375

BREAKING CHANGE: a lot of getters have been removed from the spec so
we've also removed them from this polyfill

packages/ecma402-abstract/index.ts

@@ -31,23 +31,24 @@ export {default as _formatToParts} from './NumberFormat/format_to_parts'
 export * from './PartitionPattern'
 export * from './SupportedLocales'
 export {
+  createDataProperty,
+  defineProperty,
   getInternalSlot,
+  getMagnitude,
   getMultiInternalSlots,
   isLiteralPart,
   setInternalSlot,
   setMultiInternalSlots,
-  getMagnitude,
-  defineProperty,
 } from './utils'
 export type {LiteralPart} from './utils'
 
+export * from './262'
 export {isMissingLocaleDataError} from './data'
-export * from './types/relative-time'
+export type {LocaleData} from './types/core'
 export * from './types/date-time'
+export * from './types/displaynames'
 export * from './types/list'
-export * from './types/plural-rules'
 export * from './types/number'
-export * from './types/displaynames'
+export * from './types/plural-rules'
+export * from './types/relative-time'
 export {invariant} from './utils'
-export type {LocaleData} from './types/core'
-export * from './262'

packages/ecma402-abstract/utils.ts

@@ -118,6 +118,25 @@ export function defineProperty<T extends object>(
   })
 }
 
+/**
+ * 7.3.5 CreateDataProperty
+ * @param target
+ * @param name
+ * @param value
+ */
+export function createDataProperty<T extends object>(
+  target: T,
+  name: string | symbol,
+  value: any
+) {
+  Object.defineProperty(target, name, {
+    configurable: true,
+    enumerable: true,
+    writable: true,
+    value,
+  })
+}
+
 export const UNICODE_EXTENSION_SEQUENCE_REGEX = /-u(?:-[0-9a-z]{2,8})+/gi
 
 export function invariant(

packages/intl-locale/get_internal_slots.ts

@@ -5,10 +5,23 @@ import Locale, {IntlLocaleInternal} from '.'
 
 const internalSlotMap = new WeakMap<Locale, IntlLocaleInternal>()
 
-export default function getInternalSlots(x: Locale): IntlLocaleInternal {
+export default function getInternalSlots(
+  x: Locale,
+  internalSlotsList: string[] = []
+): IntlLocaleInternal {
   let internalSlots = internalSlotMap.get(x)
   if (!internalSlots) {
-    internalSlots = Object.create(null) as IntlLocaleInternal
+    internalSlots = Object.create(
+      null,
+      internalSlotsList.reduce<PropertyDescriptorMap>((all, prop) => {
+        all[prop] = {
+          enumerable: false,
+          writable: true,
+          configurable: true,
+        }
+        return all
+      }, {})
+    ) as IntlLocaleInternal
     internalSlotMap.set(x, internalSlots)
   }
   return internalSlots