Remove unused function

Author: Kanchalai Tanglertsampan

src/compiler/core.ts

@@ -23,21 +23,6 @@ namespace ts {
     // More efficient to create a collator once and use its `compare` than to call `a.localeCompare(b)` many times.
     export const collator: { compare(a: string, b: string): number } = typeof Intl === "object" && typeof Intl.Collator === "function" ? new Intl.Collator() : undefined;
 
-    /**
-     * Use this function instead of calling "String.prototype.localeCompre". This function will preform appropriate check to make sure that
-     *  "typeof Intl" is correct as there are reported issues #11110  nad #11339.
-     * @param a reference string to compare
-     * @param b string to compare against
-     * @param locales string of BCP 47 language tag or an array of string of BCP 47 language tag
-     * @param options an object of Intl.CollatorOptions to specify localeCompare properties
-     */
-    export function localeCompare(a: string, b: string, locales?: string | string[], options?: Intl.CollatorOptions): number | undefined {
-        if (collator && String.prototype.localeCompare) {
-            return a.localeCompare(b, locales, options);
-        }
-        return undefined;
-    }
-
     export function createMap<T>(template?: MapLike<T>): Map<T> {
         const map: Map<T> = createObject(null); // tslint:disable-line:no-null-keyword