LibJS: Add tests for new Math functions

Author: https://github.com/Cleverking2003
Commit: f30d4f22ef
Pull-request: https://github.com/SerenityOS/serenity/pull/4599
Reviewed-by: https://github.com/linusg

Libraries/LibJS/Tests/builtins/Math/Math.fround.js

@@ -0,0 +1,9 @@
+test("basic functionality", () => {
+    expect(Math.fround).toHaveLength(1);
+
+    expect(Math.fround(0)).toBe(0);
+    expect(Math.fround(1)).toBe(1);
+    expect(Math.fround(1.337)).toBeCloseTo(1.3370000123977661);
+    expect(Math.fround(1.5)).toBe(1.5);
+    expect(Math.fround(NaN)).toBe(NaN);
+});