LibJS: Convert all remaining non-Array tests to the new system :)

Author: https://github.com/mattco98
Commit: 15de2eda2b
Pull-request: https://github.com/SerenityOS/serenity/pull/2689
Reviewed-by: https://github.com/linusg

Libraries/LibJS/Tests/classes/class-strict-mode.js

@@ -0,0 +1,19 @@
+test("constructors are always strict mode", () => {
+  class A {
+    constructor() {
+      expect(isStrictMode()).toBeTrue();
+    }
+  }
+
+  new A();
+});
+
+test("methods are always strict mode", () => {
+  class A {
+    method() {
+      expect(isStrictMode()).toBeTrue();
+    }
+  }
+
+  new A().method();
+});