LibJS: Fix tests that expected wrong this values

Author: https://github.com/davidot
Commit: a49b47bfe6
Pull-request: https://github.com/SerenityOS/serenity/pull/8667
Reviewed-by: https://github.com/IdanHo
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibJS/Tests/builtins/Array/Array.prototype.reduce.js

@@ -25,6 +25,11 @@ describe("errors", () => {
 describe("normal behavior", () => {
     test("basic functionality", () => {
         [1, 2].reduce(function () {
+            expect(this).toBe(globalThis);
+        });
+
+        [1, 2].reduce(function () {
+            "use strict";
             expect(this).toBeUndefined();
         });
 

Userland/Libraries/LibJS/Tests/builtins/Array/Array.prototype.reduceRight.js

@@ -25,6 +25,11 @@ describe("errors", () => {
 describe("normal behavior", () => {
     test("basic functionality", () => {
         [1, 2].reduceRight(function () {
+            expect(this).toBe(globalThis);
+        });
+
+        [1, 2].reduceRight(function () {
+            "use strict";
             expect(this).toBeUndefined();
         });