LibJS: Implement most of the Reflect object

Libraries/LibJS/Tests/Reflect.getOwnPropertyDescriptor.js

@@ -0,0 +1,35 @@
+load("test-common.js");
+
+try {
+    assert(Reflect.getOwnPropertyDescriptor.length === 2);
+
+    [null, undefined, "foo", 123, NaN, Infinity].forEach(value => {
+        assertThrowsError(() => {
+            Reflect.getOwnPropertyDescriptor(value);
+        }, {
+            error: TypeError,
+            message: "First argument of Reflect.getOwnPropertyDescriptor() must be an object"
+        });
+    });
+
+    assert(Reflect.getOwnPropertyDescriptor({}) === undefined);
+    assert(Reflect.getOwnPropertyDescriptor({}, "foo") === undefined);
+
+    var o = { foo: "bar" };
+    var d = Reflect.getOwnPropertyDescriptor(o, "foo");
+    assert(d.value === "bar");
+    assert(d.writable === true);
+    assert(d.enumerable === true);
+    assert(d.configurable === true);
+
+    var a = [];
+    d = Reflect.getOwnPropertyDescriptor(a, "length");
+    assert(d.value === 0);
+    assert(d.writable === true);
+    assert(d.enumerable === false);
+    assert(d.configurable === false);
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}