[builtins] Migrate Object.getOwnPropertyDescriptor to C++.

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index d1ed05ad0678685683cc3cd9b21b00cb27d95518..4cf93ead630d90b5653e60123e7b8850da802bc5 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -1661,6 +1661,30 @@ BUILTIN(ObjectFreeze) {
 }
 
 
+// ES6 section 19.1.2.6 Object.getOwnPropertyDescriptor ( O, P )
+BUILTIN(ObjectGetOwnPropertyDescriptor) {
+  HandleScope scope(isolate);
+  // 1. Let obj be ? ToObject(O).
+  Handle<Object> object = args.atOrUndefined(isolate, 1);
+  Handle<JSReceiver> receiver;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, receiver,
+                                     Object::ToObject(isolate, object));
+  // 2. Let key be ? ToPropertyKey(P).
+  Handle<Object> property = args.atOrUndefined(isolate, 2);
+  Handle<Name> key;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, key,
+                                     Object::ToName(isolate, property));
+  // 3. Let desc be ? obj.[[GetOwnProperty]](key).
+  PropertyDescriptor desc;
+  Maybe<bool> found =
+      JSReceiver::GetOwnPropertyDescriptor(isolate, receiver, key, &desc);
+  MAYBE_RETURN(found, isolate->heap()->exception());
+  // 4. Return FromPropertyDescriptor(desc).
+  if (!found.FromJust()) return isolate->heap()->undefined_value();
+  return *desc.ToObject(isolate);
+}
+
+
 namespace {
 
 Object* GetOwnPropertyKeys(Isolate* isolate,