Enable ES6 unscopables

test/cctest/test-unscopables-hidden-prototype.cc

 // 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.
 
 #include <stdlib.h>
 
 #include "src/v8.h"
 #include "test/cctest/cctest.h"
 
 namespace {
 
 
 static void Cleanup() {
   CompileRun(
       "delete object.x;"
       "delete hidden_prototype.x;"
       "delete object[Symbol.unscopables];"
       "delete hidden_prototype[Symbol.unscopables];");
 }
 
 
 TEST(Unscopables) {
-  i::FLAG_harmony_unscopables = true;
-
   LocalContext context;
   v8::Isolate* isolate = context->GetIsolate();
   v8::HandleScope handle_scope(isolate);
 
   v8::Local<v8::FunctionTemplate> t0 = v8::FunctionTemplate::New(isolate);
   v8::Local<v8::FunctionTemplate> t1 = v8::FunctionTemplate::New(isolate);
 
   t1->SetHiddenPrototype(true);
 
   v8::Local<v8::Object> object = t0->GetFunction()->NewInstance();
@@ skipping 61 matching lines @@
                   "var result;"
                   "var x = 0;"
                   "hidden_prototype.x = 6;"
                   "object[Symbol.unscopables] = {x: true};"
                   "with (object) {"
                   "  result = x;"
                   "}"
                   "result")->Int32Value());
 }
 }