Adds Intl.DisplayNames to es2020 - re: microsoft#44022

Author: orta

src/lib/es2020.intl.d.ts

@@ -29,6 +29,7 @@ declare namespace Intl {
         | "minutes"
         | "second"
         | "seconds";
+
     /**
      * The locale matching algorithm to use.
      *
@@ -75,7 +76,7 @@ declare namespace Intl {
     /**
      * An object with properties reflecting the locale
      * and formatting options computed during initialization
-     * of the `Intel.RelativeTimeFormat` object
+     * of the `Intl.RelativeTimeFormat` object
      *
      * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/RelativeTimeFormat/resolvedOptions#Description).
      */
@@ -150,9 +151,6 @@ declare namespace Intl {
      * The [`Intl.RelativeTimeFormat`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/RelativeTimeFormat)
      * object is a constructor for objects that enable language-sensitive relative time formatting.
      *
-     * Part of [Intl object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl)
-     * namespace and the [ECMAScript Internationalization API](https://www.ecma-international.org/publications/standards/Ecma-402.htm).
-     *
      * [Compatibility](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/RelativeTimeFormat#Browser_compatibility).
      */
     const RelativeTimeFormat: {
@@ -275,8 +273,7 @@ declare namespace Intl {
      *  For the general form and interpretation of the locales argument,
      *  see the [`Intl` page](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl#Locale_identification_and_negotiation).
      *
-     * @param options - An [object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/Locale#Parameters)
-     *  with some or all of options of the locale.
+     * @param options - An [object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/Locale#Parameters) with some or all of options of the locale.
      *
      * @returns [Intl.Locale](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale) object.
      *
@@ -285,4 +282,74 @@ declare namespace Intl {
     const Locale: {
         new (tag?: BCP47LanguageTag, options?: LocaleOptions): Locale;
     };
+
+     interface DisplayNamesOptions {
+        localeMatcher: RelativeTimeFormatLocaleMatcher;
+        style: RelativeTimeFormatStyle;
+        type: "language" | "region" | "script" | "currency";
+        fallback: "code" | "none";
+    }
+
+    interface DisplayNames {
+        /**
+         * Receives a code and returns a string based on the locale and options provided when instantiating
+         * [`Intl.DisplayNames()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames)
+         *
+         * @param code The `code` to provide depends on the `type` passed to display name during creation:
+         *  - If the type is `"region"`, code should be either an [ISO-3166 two letters region code](https://www.iso.org/iso-3166-country-codes.html),
+         *    or a [three digits UN M49 Geographic Regions](https://unstats.un.org/unsd/methodology/m49/).
+         *  - If the type is `"script"`, code should be an [ISO-15924 four letters script code](https://unicode.org/iso15924/iso15924-codes.html).
+         *  - If the type is `"language"`, code should be a `languageCode` ["-" `scriptCode`] ["-" `regionCode` ] *("-" `variant` )
+         *    subsequence of the unicode_language_id grammar in [UTS 35's Unicode Language and Locale Identifiers grammar](https://unicode.org/reports/tr35/#Unicode_language_identifier).
+         *    `languageCode` is either a two letters ISO 639-1 language code or a three letters ISO 639-2 language code.
+         *  - If the type is `"currency"`, code should be a [3-letter ISO 4217 currency code](https://www.iso.org/iso-4217-currency-codes.html).
+         *
+         * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames/of).
+         */
+        of(code: string): string;
+        /**
+         * Returns a new object with properties reflecting the locale and style formatting options computed during the construction of the current
+         * [`Intl/DisplayNames`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames) object.
+         *
+         * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames/resolvedOptions).
+         */
+        resolvedOptions(): DisplayNamesOptions;
+    }
+
+    /**
+     * The [`Intl.DisplayNames()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames)
+     * object enables the consistent translation of language, region and script display names.
+     *
+     * [Compatibility](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames#browser_compatibility).
+     */
+    const DisplayNames: {
+        prototype: DisplayNames;
+
+        /**
+         * @param locales A string with a BCP 47 language tag, or an array of such strings.
+         *   For the general form and interpretation of the `locales` argument, see the [Intl](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl#locale_identification_and_negotiation)
+         *   page.
+         *
+         * @param options An object for setting up a display name.
+         *
+         * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames/DisplayNames).
+         */
+        new(locales?: BCP47LanguageTag | BCP47LanguageTag[], options?: Partial<DisplayNamesOptions>): DisplayNames;
+
+        /**
+         * Returns an array containing those of the provided locales that are supported in display names without having to fall back to the runtime's default locale.
+         *
+         * @param locales A string with a BCP 47 language tag, or an array of such strings.
+         *   For the general form and interpretation of the `locales` argument, see the [Intl](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl#locale_identification_and_negotiation)
+         *   page.
+         *
+         * @param options An object with a locale matcher.
+         *
+         * @returns An array of strings representing a subset of the given locale tags that are supported in display names without having to fall back to the runtime's default locale.
+         *
+         * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames/supportedLocalesOf).
+         */
+        supportedLocalesOf(locales: BCP47LanguageTag | BCP47LanguageTag[], options: {localeMatcher: RelativeTimeFormatLocaleMatcher}): BCP47LanguageTag[];
+    };
+
 }