Make sure ExternalCallbackScope is always created when VM state changes to EXTERNAL

src/handles.cc

Index: src/handles.cc
diff --git a/src/handles.cc b/src/handles.cc
index 6859cd423fb47512c74bd87c1b7909e16875fd9e..382b3fbedfc733dd9735b3ff34f24d811eddaf01 100644
--- a/src/handles.cc
+++ b/src/handles.cc
@@ -557,11 +557,7 @@ v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSReceiver> receiver,
     v8::NamedPropertyEnumerator enum_fun =
         v8::ToCData<v8::NamedPropertyEnumerator>(interceptor->enumerator());
     LOG(isolate, ApiObjectAccess("interceptor-named-enum", *object));
-    {
-      // Leaving JavaScript.
-      VMState<EXTERNAL> state(isolate);
-      result = args.Call(enum_fun);
-    }
+    result = args.Call(enum_fun);
   }
 #if ENABLE_EXTRA_CHECKS
   CHECK(result.IsEmpty() || v8::Utils::OpenHandle(*result)->IsJSObject());
@@ -583,14 +579,10 @@ v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSReceiver> receiver,
     v8::IndexedPropertyEnumerator enum_fun =
         v8::ToCData<v8::IndexedPropertyEnumerator>(interceptor->enumerator());
     LOG(isolate, ApiObjectAccess("interceptor-indexed-enum", *object));
-    {
-      // Leaving JavaScript.
-      VMState<EXTERNAL> state(isolate);
-      result = args.Call(enum_fun);
+    result = args.Call(enum_fun);
 #if ENABLE_EXTRA_CHECKS
-      CHECK(result.IsEmpty() || v8::Utils::OpenHandle(*result)->IsJSObject());
+    CHECK(result.IsEmpty() || v8::Utils::OpenHandle(*result)->IsJSObject());
 #endif
-    }
   }
   return v8::Local<v8::Array>::New(reinterpret_cast<v8::Isolate*>(isolate),
                                    result);