LibJS: Add BigInt equality tests for some large numbers

Author: https://github.com/linusg
Commit: 4e2a961a3d
Pull-request: https://github.com/SerenityOS/serenity/pull/5339
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibJS/Tests/builtins/BigInt/bigint-basic.js

@@ -54,6 +54,11 @@ describe("correct behavior", () => {
         expect(1 != 1n).toBeFalse();
         expect(1n != 1.23).toBeTrue();
         expect(1.23 != 1n).toBeTrue();
+
+        const a = 552141064586571465517761649840658n;
+        const b = 704179908449526267977309288010258n;
+        expect(a == a).toBeTrue();
+        expect(a == b).toBeFalse();
     });
 
     test("strong equality operators", () => {
@@ -68,6 +73,11 @@ describe("correct behavior", () => {
         expect(1 !== 1n).toBeTrue();
         expect(1n !== 1.23).toBeTrue();
         expect(1.23 !== 1n).toBeTrue();
+
+        const a = 552141064586571465517761649840658n;
+        const b = 704179908449526267977309288010258n;
+        expect(a === a).toBeTrue();
+        expect(a === b).toBeFalse();
     });
 });