LibWeb: Implement document ready state

Libraries/LibWeb/Tests/HTML/document.readyState.js

@@ -0,0 +1,31 @@
+loadPage("file:///res/html/misc/blank.html");
+
+beforeInitialPageLoad(() => {
+    window.events = [];
+
+    document.addEventListener("readystatechange", () => {
+        window.events.push(document.readyState);
+    });
+
+    document.addEventListener("DOMContentLoaded", () => {
+        test("Ready state should be 'interactive' when 'DOMContentLoaded' fires", () => {
+            expect(document.readyState).toBe("interactive");
+        });
+    });
+
+    test("Ready state should be 'loading' initially", () => {
+        expect(document.readyState).toBe("loading");
+    });
+});
+
+afterInitialPageLoad(() => {
+    test("'interactive' should come before 'complete' and both should have happened", () => {
+        expect(window.events).toHaveLength(2);
+        expect(window.events[0]).toBe("interactive");
+        expect(window.events[1]).toBe("complete");
+    });
+
+    test("Ready state should be 'complete' after loading", () => {
+        expect(document.readyState).toBe("complete");
+    });
+});