IDL: Add support for [TreatNullAs=EmptyString]

Source/bindings/core/v8/ScriptEventListener.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 104 matching lines @@
     V8AbstractEventListener* v8Listener = static_cast<V8AbstractEventListener*>(listener);
     v8::Handle<v8::Context> context = toV8Context(document, v8Listener->world());
     v8::Context::Scope contextScope(context);
     v8::Handle<v8::Object> object = v8Listener->getListenerObject(document);
     if (object.IsEmpty())
         return "";
     v8::Handle<v8::Function> function = eventListenerEffectiveFunction(scope.GetIsolate(), object);
     if (function.IsEmpty())
         return "";
 
-    TOSTRING_DEFAULT(V8StringResource<WithNullCheck>, functionString, function, "");
+    TOSTRING_DEFAULT(V8StringResource<TreatNullAsNullString>, functionString, function, "");
     return functionString;
 }
 
 ScriptValue eventListenerHandler(Document* document, EventListener* listener)
 {
     if (listener->type() != EventListener::JSEventListenerType)
         return ScriptValue();
 
     v8::Isolate* isolate = toIsolate(document);
     v8::HandleScope scope(isolate);
@@ skipping 37 matching lines @@
     v8::ScriptOrigin origin = originalFunction->GetScriptOrigin();
     if (!origin.ResourceName().IsEmpty() && origin.ResourceName()->IsString())
         sourceName = toCoreString(origin.ResourceName().As<v8::String>());
     else
         sourceName = "";
     lineNumber = originalFunction->GetScriptLineNumber();
     return true;
 }
 
 } // namespace WebCore