fix(tsc): Add typings for Intl.ListFormat (#13301)

V8 has supported `Intl.ListFormat` since version 7.2, but TypeScript doesn't
have typings for it yet. This PR manually adds those typings, copying them from
microsoft/TypeScript#47254.

cli/dts/lib.es2021.intl.d.ts

@@ -41,4 +41,106 @@ declare namespace Intl {
         formatRange(startDate: number | bigint, endDate: number | bigint): string;
         formatRangeToParts(startDate: number | bigint, endDate: number | bigint): NumberFormatPart[];
     }
+
+    /**
+     * The locale matching algorithm to use.
+     *
+     * [MDN](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Intl#Locale_negotiation).
+     */
+    type ListFormatLocaleMatcher = "lookup" | "best fit";
+
+     /**
+      * The format of output message.
+      *
+      * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/ListFormat/ListFormat#parameters).
+      */
+    type ListFormatType = "conjunction" | "disjunction" | "unit";
+ 
+     /**
+      * The length of the formatted message.
+      *
+      * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/ListFormat/ListFormat#parameters).
+      */
+    type ListFormatStyle = "long" | "short" | "narrow";
+ 
+     /**
+      * An object with some or all properties of the `Intl.ListFormat` constructor `options` parameter.
+      *
+      * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/ListFormat/ListFormat#parameters).
+      */
+    interface ListFormatOptions {
+        /** The locale matching algorithm to use. For information about this option, see [Intl page](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Intl#Locale_negotiation). */
+        localeMatcher?: ListFormatLocaleMatcher;
+        /** The format of output message. */
+        type?: ListFormatType;
+        /** The length of the internationalized message. */
+        style?: ListFormatStyle;
+    }
+ 
+    interface ListFormat {
+        /**
+         * Returns a string with a language-specific representation of the list.
+         *
+         * @param list - An iterable object, such as an [Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array).
+         *
+         * @throws `TypeError` if `list` includes something other than the possible values.
+         *
+         * @returns {string} A language-specific formatted string representing the elements of the list.
+         *
+         * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/ListFormat/format).
+         */
+        format(list: Iterable<string>): string;
+
+        /**
+         * Returns an Array of objects representing the different components that can be used to format a list of values in a locale-aware fashion.
+         *
+         * @param list - An iterable object, such as an [Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array), to be formatted according to a locale.
+         *
+         * @throws `TypeError` if `list` includes something other than the possible values.
+         *
+         * @returns {{ type: "element" | "literal", value: string; }[]} An Array of components which contains the formatted parts from the list.
+         *
+         * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/ListFormat/formatToParts).
+         */
+        formatToParts(list: Iterable<string>): { type: "element" | "literal", value: string; }[];
+    }
+
+    const ListFormat: {
+        prototype: ListFormat;
+
+        /**
+         * Creates [Intl.ListFormat](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/ListFormat) objects that
+         * enable language-sensitive list formatting.
+         *
+         * @param locales - A string with a [BCP 47 language tag](http://tools.ietf.org/html/rfc5646), or an array of such strings.
+         *  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/ListFormat/ListFormat#parameters)
+         *  with some or all options of `ListFormatOptions`.
+         *
+         * @returns [Intl.ListFormatOptions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/ListFormat) object.
+         *
+         * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/ListFormat).
+         */
+        new(locales?: BCP47LanguageTag | BCP47LanguageTag[], options?: ListFormatOptions): ListFormat;
+
+        /**
+         * Returns an array containing those of the provided locales that are
+         * supported in list formatting without having to fall back to the runtime's default locale.
+         *
+         * @param locales - A string with a [BCP 47 language tag](http://tools.ietf.org/html/rfc5646), or an array of such strings.
+         *  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/ListFormat/supportedLocalesOf#parameters).
+         *  with some or all possible options.
+         *
+         * @returns An array of strings representing a subset of the given locale tags that are supported in list
+         *  formatting 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/ListFormat/supportedLocalesOf).
+         */
+        supportedLocalesOf(locales: BCP47LanguageTag | BCP47LanguageTag[], options?: Pick<ListFormatOptions, "localeMatcher">): BCP47LanguageTag[];
+    };
 }

cli/tests/unit/esnext_test.ts

@@ -23,3 +23,35 @@ Deno.test(function errorCause() {
   const e = new Error("test", { cause: "something" });
   assertEquals(e.cause, "something");
 });
+
+Deno.test(function intlListFormat() {
+  const formatter = new Intl.ListFormat("en", {
+    style: "long",
+    type: "conjunction",
+  });
+  assertEquals(
+    formatter.format(["red", "green", "blue"]),
+    "red, green, and blue",
+  );
+
+  const formatter2 = new Intl.ListFormat("en", {
+    style: "short",
+    type: "disjunction",
+  });
+  assertEquals(formatter2.formatToParts(["Rust", "golang"]), [
+    { type: "element", value: "Rust" },
+    { type: "literal", value: " or " },
+    { type: "element", value: "golang" },
+  ]);
+
+  // Works with iterables as well
+  assertEquals(
+    formatter.format(new Set(["red", "green", "blue"])),
+    "red, green, and blue",
+  );
+  assertEquals(formatter2.formatToParts(new Set(["Rust", "golang"])), [
+    { type: "element", value: "Rust" },
+    { type: "literal", value: " or " },
+    { type: "element", value: "golang" },
+  ]);
+});