LibJS: Implement Temporal.Duration.prototype.sign/blank

Author: https://github.com/trflynn89
Commit: dfaa3bf649
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2431
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/shannonbooth ✅

Libraries/LibJS/Tests/builtins/Temporal/Duration/Duration.prototype.blank.js

@@ -0,0 +1,17 @@
+describe("correct behavior", () => {
+    test("basic functionality", () => {
+        const nonBlankDuration = new Temporal.Duration(123);
+        expect(nonBlankDuration.blank).toBeFalse();
+
+        const blankDuration = new Temporal.Duration(0);
+        expect(blankDuration.blank).toBeTrue();
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.Duration object", () => {
+        expect(() => {
+            Reflect.get(Temporal.Duration.prototype, "blank", "foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.Duration");
+    });
+});

Libraries/LibJS/Tests/builtins/Temporal/Duration/Duration.prototype.sign.js

@@ -0,0 +1,17 @@
+describe("correct behavior", () => {
+    test("basic functionality", () => {
+        const positiveDuration = new Temporal.Duration(123);
+        expect(positiveDuration.sign).toBe(1);
+
+        const negativeDuration = new Temporal.Duration(-123);
+        expect(negativeDuration.sign).toBe(-1);
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.Duration object", () => {
+        expect(() => {
+            Reflect.get(Temporal.Duration.prototype, "sign", "foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.Duration");
+    });
+});