Revert of [builtins] Also port the Object.prototype.__proto__ accessors to C++.

src/js/v8natives.js

Index: src/js/v8natives.js
diff --git a/src/js/v8natives.js b/src/js/v8natives.js
index 9098e82bf2424b6733748f8956bfaff8a0709313..3ba39cf4b76051cfab6f28fda7d7eba706b690a7 100644
--- a/src/js/v8natives.js
+++ b/src/js/v8natives.js
@@ -104,6 +104,22 @@
   throw %make_type_error(kCalledNonCallable, typeof func);
 }
 
+// ES6 B.2.2.1.1
+function ObjectGetProto() {
+  return %object_get_prototype_of(this);
+}
+
+
+// ES6 B.2.2.1.2
+function ObjectSetProto(proto) {
+  CHECK_OBJECT_COERCIBLE(this, "Object.prototype.__proto__");
+
+  if ((IS_RECEIVER(proto) || IS_NULL(proto)) && IS_RECEIVER(this)) {
+    %SetPrototype(this, proto);
+  }
+}
+
+
 // ES6 19.1.1.1
 function ObjectConstructor(x) {
   if (GlobalObject != new.target && !IS_UNDEFINED(new.target)) {
@@ -135,6 +151,8 @@
   // __defineSetter__ is added in bootstrapper.cc.
   // __lookupSetter__ is added in bootstrapper.cc.
 ]);
+utils.InstallGetterSetter(
+    GlobalObject.prototype, "__proto__", ObjectGetProto, ObjectSetProto);
 
 
 // ----------------------------------------------------------------------------