Throw exception for null listener in addEventListener

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"
 
 namespace blink {
 
 DartExceptionFactory::DartExceptionFactory(DartState* dart_state)
     : dart_state_(dart_state) {
 }
 
 DartExceptionFactory::~DartExceptionFactory() {
 }
 
+Dart_Handle DartExceptionFactory::CreateNullArgumentException(int index) {
+  StringBuilder message;
+  message.appendLiteral("Argument ");
+  message.appendNumber(index);
+  message.appendLiteral(" cannot be null.");
+  return CreateException("ArgumentError", message.toString());
+}
+
 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);
 }
 
 }  // namespace blink