[bootstrapper] clear extras utils object after usage.

src/bootstrapper.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 "src/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/base/ieee754.h"
 #include "src/code-stubs.h"
@@ skipping 3110 matching lines @@
       if (natives_key->AsArrayIndex(&dummy_index)) break;
       Handle<Object> utils = isolate()->natives_utils_object();
       Handle<JSObject> global = isolate()->global_object();
       JSObject::AddProperty(global, natives_key, utils, DONT_ENUM);
       break;
     }
   }
 
   // The utils object can be removed for cases that reach this point.
   native_context()->set_natives_utils_object(heap()->undefined_value());
+  native_context()->set_extras_utils_object(heap()->undefined_value());
 }
 
 
 void Bootstrapper::ExportFromRuntime(Isolate* isolate,
                                      Handle<JSObject> container) {
   Factory* factory = isolate->factory();
   HandleScope scope(isolate);
   Handle<Context> native_context = isolate->native_context();
 #define EXPORT_PRIVATE_SYMBOL(NAME)                                       \
   Handle<String> NAME##_name = factory->NewStringFromAsciiChecked(#NAME); \
@@ skipping 1699 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8