1 files changed, 43 insertions, 8 deletions

diff --git a/cli/dts/lib.es2020.intl.d.ts b/cli/dts/lib.es2020.intl.d.ts
index 3e47f89cf..af981e31c 100644
--- a/cli/dts/lib.es2020.intl.d.ts
+++ b/cli/dts/lib.es2020.intl.d.ts
@@ -79,6 +79,13 @@ declare namespace Intl {
     type BCP47LanguageTag = string;
 
     /**
+     * The locale(s) to use
+     *
+     * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl#locales_argument).
+     */
+    type LocalesArgument = UnicodeBCP47LocaleIdentifier | Locale | (UnicodeBCP47LocaleIdentifier | Locale)[] | undefined;
+
+    /**
      * An object with some or all of properties of `options` parameter
      * of `Intl.RelativeTimeFormat` constructor.
      *
@@ -274,6 +281,10 @@ declare namespace Intl {
     }
 
     interface Locale extends LocaleOptions {
+        /** A string containing the language, and the script and region if available. */
+        baseName: string;
+        /** The primary language subtag associated with the locale. */
+        language: string;
         /** Gets the most likely values for the language, script, and region of the locale based on existing values. */
         maximize(): Locale;
         /** Attempts to remove information about the locale that would be added by calling `Locale.maximize()`. */
@@ -297,15 +308,39 @@ declare namespace Intl {
      * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale).
      */
     const Locale: {
-        new (tag?: BCP47LanguageTag, options?: LocaleOptions): Locale;
+        new (tag: BCP47LanguageTag | Locale, options?: LocaleOptions): Locale;
     };
 
-     interface DisplayNamesOptions {
+    type DisplayNamesFallback =
+        | "code"
+        | "none";
+
+    type DisplayNamesType =
+        | "language"
+        | "region"
+        | "script"
+        | "calendar"
+        | "dateTimeField"
+        | "currency";
+
+    type DisplayNamesLanguageDisplay =
+        | "dialect"
+        | "standard";
+
+    interface DisplayNamesOptions {
+        localeMatcher?: RelativeTimeFormatLocaleMatcher;
+        style?: RelativeTimeFormatStyle;
+        type: DisplayNamesType;
+        languageDisplay?: DisplayNamesLanguageDisplay;
+        fallback?: DisplayNamesFallback;
+    }
+
+    interface ResolvedDisplayNamesOptions {
         locale: UnicodeBCP47LocaleIdentifier;
-        localeMatcher: RelativeTimeFormatLocaleMatcher;
         style: RelativeTimeFormatStyle;
-        type: "language" | "region" | "script" | "currency";
-        fallback: "code" | "none";
+        type: DisplayNamesType;
+        fallback: DisplayNamesFallback;
+        languageDisplay?: DisplayNamesLanguageDisplay;
     }
 
     interface DisplayNames {
@@ -331,7 +366,7 @@ declare namespace Intl {
          *
          * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames/resolvedOptions).
          */
-        resolvedOptions(): DisplayNamesOptions;
+        resolvedOptions(): ResolvedDisplayNamesOptions;
     }
 
     /**
@@ -352,7 +387,7 @@ declare namespace Intl {
          *
          * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames/DisplayNames).
          */
-        new(locales?: BCP47LanguageTag | BCP47LanguageTag[], options?: Partial<DisplayNamesOptions>): DisplayNames;
+        new(locales: LocalesArgument, options: 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.
@@ -367,7 +402,7 @@ declare namespace Intl {
          *
          * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames/supportedLocalesOf).
          */
-        supportedLocalesOf(locales: BCP47LanguageTag | BCP47LanguageTag[], options?: {localeMatcher: RelativeTimeFormatLocaleMatcher}): BCP47LanguageTag[];
+        supportedLocalesOf(locales?: LocalesArgument, options?: { localeMatcher?: RelativeTimeFormatLocaleMatcher }): BCP47LanguageTag[];
     };
 
 }