LibJS: Implement most of the Reflect object

Libraries/LibJS/Tests/Reflect.defineProperty.js

@@ -0,0 +1,59 @@
+load("test-common.js");
+
+try {
+    assert(Reflect.defineProperty.length === 3);
+
+    [null, undefined, "foo", 123, NaN, Infinity].forEach(value => {
+        assertThrowsError(() => {
+            Reflect.defineProperty(value);
+        }, {
+            error: TypeError,
+            message: "First argument of Reflect.defineProperty() must be an object"
+        });
+
+        assertThrowsError(() => {
+            Reflect.defineProperty({}, "foo", value);
+        }, {
+            error: TypeError,
+            message: "Descriptor argument is not an object"
+        });
+    });
+
+    var o = {};
+
+    assert(Reflect.defineProperty(o, "foo", { value: 1, writable: false, enumerable: false }) === true);
+    assert(o.foo === 1);
+    o.foo = 2;
+    assert(o.foo === 1);
+
+    assert(Reflect.defineProperty(o, "bar", { value: "hi", writable: true, enumerable: true }) === true);
+    assert(o.bar === "hi");
+    o.bar = "ho";
+    assert(o.bar === "ho");
+
+    assert(Reflect.defineProperty(o, "bar", { value: "xx", enumerable: false }) === false);
+
+    var d = Reflect.getOwnPropertyDescriptor(o, "foo");
+    assert(d.configurable === false);
+    assert(d.enumerable === false);
+    assert(d.writable === false);
+    assert(d.value === 1);
+
+    d = Reflect.getOwnPropertyDescriptor(o, "bar");
+    assert(d.configurable === false);
+    assert(d.enumerable === true);
+    assert(d.writable === true);
+    assert(d.value === "ho");
+
+    assert(Reflect.defineProperty(o, "baz", { value: 9, configurable: true, writable: false }) === true);
+    assert(Reflect.defineProperty(o, "baz", { configurable: true, writable: true }) === true);
+
+    d = Reflect.getOwnPropertyDescriptor(o, "baz");
+    assert(d.configurable === true);
+    assert(d.writable === true);
+    assert(d.value === 9);
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}