Implement Intl Locale Info proposal

Author: printfn

src/lib/esnext.intl.d.ts

@@ -1,3 +1,87 @@
 declare namespace Intl {
-    // Empty
+    interface Locale {
+        /**
+         * Returns a list of one or more unique calendar identifiers for this locale.
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getCalendars)
+         */
+        getCalendars(): string[];
+        /**
+         * Returns a list of one or more collation types for this locale.
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getCollations)
+         */
+        getCollations(): string[];
+        /**
+         * Returns a list of one or more unique hour cycle identifiers for this locale.
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getHourCycles)
+         */
+        getHourCycles(): string[];
+        /**
+         * Returns a list of one or more unique numbering system identifiers for this locale.
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getNumberingSystems)
+         */
+        getNumberingSystems(): string[];
+        /**
+         * Returns the ordering of characters indicated by either ltr (left-to-right) or by rtl (right-to-left) for this locale.
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getTextInfo)
+         */
+        getTextInfo(): TextInfo;
+        /**
+         * Returns a list of supported time zones for this locale.
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getTimeZones)
+         */
+        getTimeZones(): string[];
+        /**
+         * Returns a `WeekInfo` object with the properties `firstDay`, `weekend` and `minimalDays` for this locale.
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getWeekInfo)
+         */
+        getWeekInfo(): WeekInfo;
+    }
+
+    /**
+     * An object representing text typesetting information associated with the Locale data specified in UTS 35's Layouts Elements.
+     *
+     * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getTextInfo#return_value)
+     */
+    interface TextInfo {
+        /**
+         * A string indicating the direction of text for the locale. Can be either "ltr" (left-to-right) or "rtl" (right-to-left).
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getTextInfo#direction)
+         */
+        direction: "ltr" | "rtl";
+    }
+
+    /**
+     * An object representing week information associated with the Locale data specified in UTS 35's Week Elements.
+     *
+     * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getWeekInfo#return_value)
+     */
+    interface WeekInfo {
+        /**
+         * An integer between 1 (Monday) and 7 (Sunday) indicating the first day of the week for the locale. Commonly 1, 5, 6, or 7.
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getWeekInfo#firstday)
+         */
+        firstDay: number;
+        /**
+         * An array of integers between 1 and 7 indicating the weekend days for the locale.
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getWeekInfo#weekend)
+         */
+        weekend: number[];
+        /**
+         * An integer between 1 and 7 (commonly 1 and 4) indicating the minimal days required in the
+         * first week of a month or year, for week-of-year or week-of-month calculations (e.g. The 20th week of the year).
+         *
+         * [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getWeekInfo#minimaldays)
+         */
+        minimalDays: number;
+    }
 }