Use Dart_EmptyString

sky/engine/tonic/dart_exception_factory.cc

 // Copyright 2015 The Chromium 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 "sky/engine/config.h"
 #include "sky/engine/tonic/dart_exception_factory.h"
 
 #include "sky/engine/tonic/dart_converter.h"
 #include "sky/engine/tonic/dart_builtin.h"
 #include "sky/engine/wtf/text/StringBuilder.h"
@@ skipping 18 matching lines @@
 Dart_Handle DartExceptionFactory::CreateException(const String& class_name,
                                                   const String& message) {
   if (core_library_.is_empty()) {
     Dart_Handle library = DartBuiltin::LookupLibrary("dart:core");
     core_library_.Set(dart_state_, library);
   }
 
   Dart_Handle exception_class = Dart_GetType(
       core_library_.value(), StringToDart(dart_state_, class_name), 0, 0);
   Dart_Handle message_handle = StringToDart(dart_state_, message);
-  Dart_Handle empty_string = Dart_NewStringFromCString("");
-  return Dart_New(exception_class, empty_string, 1, &message_handle);
+  return Dart_New(exception_class, Dart_EmptyString(), 1, &message_handle);
 }
 
 }  // namespace blink