Simplify invokeCallback() and support void return values for IDL callbacks

Source/core/inspector/InspectorDatabaseAgent.cpp

 /*
  * Copyright (C) 2010 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 166 matching lines @@
 
 class TransactionSuccessCallback : public VoidCallback {
 public:
     static PassOwnPtr<TransactionSuccessCallback> create()
     {
         return adoptPtr(new TransactionSuccessCallback());
     }
 
     virtual ~TransactionSuccessCallback() { }
 
-    virtual bool handleEvent() { return false; }
+    virtual void handleEvent() { }
 
 private:
     TransactionSuccessCallback() { }
 };
 
 } // namespace
 
 void InspectorDatabaseAgent::didOpenDatabase(PassRefPtr<Database> database, const String& domain, const String& name, const String& version)
 {
     if (InspectorDatabaseResource* resource = findByFileName(database->fileName())) {
@@ skipping 124 matching lines @@
 
 Database* InspectorDatabaseAgent::databaseForId(const String& databaseId)
 {
     DatabaseResourcesMap::iterator it = m_resources.find(databaseId);
     if (it == m_resources.end())
         return 0;
     return it->value->database();
 }
 
 } // namespace WebCore