LibJS: Implement most of the Reflect object

Libraries/LibJS/Tests/Reflect.deleteProperty.js

@@ -0,0 +1,47 @@
+load("test-common.js");
+
+try {
+    assert(Reflect.deleteProperty.length === 2);
+
+    [null, undefined, "foo", 123, NaN, Infinity].forEach(value => {
+        assertThrowsError(() => {
+            Reflect.deleteProperty(value);
+        }, {
+            error: TypeError,
+            message: "First argument of Reflect.deleteProperty() must be an object"
+        });
+    });
+
+    assert(Reflect.deleteProperty({}) === true);
+    assert(Reflect.deleteProperty({}, "foo") === true);
+
+    var o = { foo: 1 };
+    assert(o.foo === 1);
+    assert(Reflect.deleteProperty(o, "foo") === true);
+    assert(o.foo === undefined);
+    assert(Reflect.deleteProperty(o, "foo") === true);
+    assert(o.foo === undefined);
+
+    Object.defineProperty(o, "bar", { value: 2, configurable: true, writable: false });
+    assert(Reflect.deleteProperty(o, "bar") === true);
+    assert(o.bar === undefined);
+
+    Object.defineProperty(o, "baz", { value: 3, configurable: false, writable: true });
+    assert(Reflect.deleteProperty(o, "baz") === false);
+    assert(o.baz === 3);
+
+    var a = [1, 2, 3];
+    assert(a.length === 3);
+    assert(a[0] === 1);
+    assert(a[1] === 2);
+    assert(a[2] === 3);
+    assert(Reflect.deleteProperty(a, 1) === true);
+    assert(a.length === 3);
+    assert(a[0] === 1);
+    assert(a[1] === undefined);
+    assert(a[2] === 3);
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}