[es6] implement Object.assign

src/harmony-object.js

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+// ES6, draft 10-14-14, section 19.1.2.1
+function ObjectAssign(target, sources) {
+  var to = ToObject(target);
+  var argsLen = %_ArgumentsLength();
+  if (argsLen < 2) return to;
+
+  for (var i = 1; i < argsLen; ++i) {
+    var nextSource = %_Arguments(i);
+    if (IS_NULL_OR_UNDEFINED(nextSource)) {
+      continue;
+    }
+
+    var from = ToObject(nextSource);
+    var keys = ObjectGetOwnPropertyKeys(from);
+    var len = keys.length;
+
+    for (var j = 0; j < len; ++j) {
+      var key = keys[j];
+      if (ObjectPropertyIsEnumerableJS(from, key)) {

[arv (Not doing code reviews), 2014/12/02 19:16:06]

You can do %_CallFunction here so you do not need to change v8natives.js

[caitp (gmail), 2014/12/02 19:39:01]

Done --- It's much harder to read like this though :>

+        var propValue = from[key];
+        %SetProperty(to, key, propValue, kStrictMode);

[arv (Not doing code reviews), 2014/12/02 19:16:06]

I don't think this needs a runtime.

to[key] = propValue;

[caitp (gmail), 2014/12/02 19:39:01]

Done.

+      }
+    }
+  }
+  return to;
+}
+
+
+function HarmonyObjectExtendObjectPrototype() {
+  %CheckIsBootstrapping();
+
+  // Set up non-enumerable functions on the Object object.
+  InstallFunctions($Object, DONT_ENUM, $Array(
+    "assign", ObjectAssign
+  ));
+}
+
+HarmonyObjectExtendObjectPrototype();