[es6] Fix Object built-in subclassing.

BUG=v8:3886
LOG=Y

Review URL: https://codereview.chromium.org/1422853004

Cr-Commit-Position: refs/heads/master@{#31760}

src/js/v8natives.js

@@ -1311,14 +1311,13 @@ function ObjectSetProto(proto) {
 }
 
 
+// ECMA-262, Edition 6, section 19.1.1.1
 function ObjectConstructor(x) {
-  if (%_IsConstructCall()) {
-    if (x == null) return this;
-    return TO_OBJECT(x);
-  } else {
-    if (x == null) return { };
-    return TO_OBJECT(x);
+  if (GlobalObject != new.target && !IS_UNDEFINED(new.target)) {
+    return this;
   }
+  if (IS_NULL(x) || IS_UNDEFINED(x)) return {};
+  return TO_OBJECT(x);
 }
 
 

test/mjsunit/es6/classes-subclass-builtins.js

@@ -17,6 +17,55 @@ function checkPrototypeChain(object, constructors) {
 }
 
 
+(function() {
+  class A extends Object {
+    constructor(...args) {
+      assertTrue(%IsConstructCall());
+      super(...args);
+      this.a = 42;
+      this.d = 4.2;
+    }
+  }
+
+  var s = new A("foo");
+  assertTrue(s instanceof Object);
+  assertTrue(s instanceof A);
+  assertEquals("object", typeof s);
+  checkPrototypeChain(s, [A, Object]);
+  assertEquals(42, s.a);
+  assertEquals(4.2, s.d);
+
+  var s1 = new A("bar");
+  assertTrue(%HaveSameMap(s, s1));
+
+
+  var n = new A(153);
+  assertTrue(n instanceof Object);
+  assertTrue(n instanceof A);
+  assertEquals("object", typeof s);
+  checkPrototypeChain(s, [A, Object]);
+  assertEquals(42, n.a);
+  assertEquals(4.2, n.d);
+
+  var n1 = new A(312);
+  assertTrue(%HaveSameMap(n, n1));
+  assertTrue(%HaveSameMap(n, s));
+
+
+  var b = new A(true);
+  assertTrue(b instanceof Object);
+  assertTrue(b instanceof A);
+  assertEquals("object", typeof s);
+  checkPrototypeChain(s, [A, Object]);
+  assertEquals(42, b.a);
+  assertEquals(4.2, b.d);
+
+  var b1 = new A(true);
+  assertTrue(%HaveSameMap(b, b1));
+  assertTrue(%HaveSameMap(b, s));
+})();
+
+
 (function() {
   class A extends Function {
     constructor(...args) {

test/mjsunit/es6/super.js

@@ -1978,8 +1978,8 @@ TestKeyedSetterCreatingOwnPropertiesNonConfigurable(42, 43, 44);
   class F extends Object { }
   var f = new F(42);
 
-  // TODO(dslomov,arv): Fix this. BUG=v8:3886.
-  assertInstanceof(f, Number);
+  assertInstanceof(f, F);
+  assertInstanceof(f, Object);
 }());