[js] Add externs for `Intl.ListFormat` class (#10356)

* [js] Add externs for `Intl.ListFormat` class

Fixes #10354

* [js] The `list` parameter of the `Intl.ListFormat.formatToParts()` method is optional

std/js/lib/intl/ListFormat.hx

@@ -0,0 +1,121 @@
+/*
+ * Copyright (C)2005-2021 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package js.lib.intl;
+
+/**
+	The `Intl.ListFormat` object enables language-sensitive list formatting.
+**/
+@:native("Intl.ListFormat")
+extern class ListFormat {
+
+	/**
+		Creates a new `Intl.ListFormat` object.
+	**/
+	@:overload(function(?locales: Array<String>, ?options: ListFormatOptions): Void {})
+	function new(?locales: String, ?options: ListFormatOptions);
+
+	/**
+		Returns a language-specific formatted string representing the elements of the list.
+	**/
+	function format(?list: Array<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.
+	**/
+	function formatToParts(?list: Array<String>): Array<ListFormatPart>;
+
+	/**
+		Returns an array containing those of the provided locales that are supported
+		without having to fall back to the runtime's default locale.
+	**/
+	@:overload(function(locales: Array<String>, ?options: ListFormatSupportedLocalesOfOptions): Array<String> {})
+	static function supportedLocalesOf(locales: String, ?options: ListFormatSupportedLocalesOfOptions): Array<String>;
+}
+
+typedef ListFormatOptions = {
+	/**
+		The locale matching algorithm to use.
+		The default is `BestFit`.
+	**/
+	var ?localeMatcher: LocaleMatcher;
+
+	/**
+		The length of the formatted message.
+		The default is `Long`.
+	**/
+	var ?style: ListFormatStyle;
+
+	/**
+		The format of output message.
+	**/
+	var ?type: ListFormatType;
+}
+
+typedef ListFormatPart = {
+	final type: ListFormatPartType;
+	final value: String;
+}
+
+enum abstract ListFormatPartType(String) {
+	/**
+		A value from the list.
+	**/
+	var Element = "element";
+
+	/**
+		A linguistic construct.
+	**/
+	var Literal = "literal";
+}
+
+enum abstract ListFormatStyle(String) {
+	var Long = "long";
+	var Narrow = "narrow";
+	var Short = "short";
+}
+
+typedef ListFormatSupportedLocalesOfOptions = {
+	/**
+		The locale matching algorithm to use.
+		The default is `BestFit`.
+	 */
+	var ?localeMatcher: LocaleMatcher;
+}
+
+enum abstract ListFormatType(String) {
+	/**
+		Stands for "and"-based lists.
+	**/
+	var Conjunction = "conjunction";
+
+	/**
+		Stands for "or"-based lists.
+	**/
+	var Disjunction = "disjunction";
+
+	/**
+		Stands for lists of values with units.
+	**/
+	var Unit = "unit";
+}