[es6] Object.getPrototypeOf should work with values

src/v8natives.js

 // Copyright 2012 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.
 
 // This file relies on the fact that the following declarations have been made
 // in runtime.js:
 // var $Object = global.Object;
 // var $Boolean = global.Boolean;
 // var $Number = global.Number;
 // var $Function = global.Function;
@@ skipping 958 matching lines @@
     var attributes = FromGenericPropertyDescriptor(desc);
     return DefineProxyProperty(obj, p, attributes, should_throw);
   } else if (IS_ARRAY(obj)) {
     return DefineArrayProperty(obj, p, desc, should_throw);
   } else {
     return DefineObjectProperty(obj, p, desc, should_throw);
   }
 }
 
 
-// ES5 section 15.2.3.2.
+// ES6 section 19.1.2.9
 function ObjectGetPrototypeOf(obj) {
-  if (!IS_SPEC_OBJECT(obj)) {
-    throw MakeTypeError("called_on_non_object", ["Object.getPrototypeOf"]);
-  }
-  return %_GetPrototype(obj);
+  return %_GetPrototype(TO_OBJECT_INLINE(obj));
 }
 
 // ES6 section 19.1.2.19.
 function ObjectSetPrototypeOf(obj, proto) {
   CHECK_OBJECT_COERCIBLE(obj, "Object.setPrototypeOf");
 
   if (proto !== null && !IS_SPEC_OBJECT(proto)) {
     throw MakeTypeError("proto_object_or_null", [proto]);
   }
 
@@ skipping 899 matching lines @@
   }
   if (!IS_SPEC_FUNCTION(method)) {
     throw MakeTypeError('not_iterable', [obj]);
   }
   var iterator = %_CallFunction(obj, method);
   if (!IS_SPEC_OBJECT(iterator)) {
     throw MakeTypeError('not_an_iterator', [iterator]);
   }
   return iterator;
 }