Extract a DOMWindow interface from LocalDOMWindow and use it in the idl.

Source/modules/webdatabase/DOMWindowWebDatabase.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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 22 matching lines @@
 #include "core/dom/ExceptionCode.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "modules/webdatabase/Database.h"
 #include "modules/webdatabase/DatabaseCallback.h"
 #include "modules/webdatabase/DatabaseManager.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/weborigin/SecurityOrigin.h"
 
 namespace blink {
 
-Database* DOMWindowWebDatabase::openDatabase(LocalDOMWindow& window, const String& name, const String& version, const String& displayName, unsigned long estimatedSize, DatabaseCallback* creationCallback, ExceptionState& exceptionState)
+Database* DOMWindowWebDatabase::openDatabase(DOMWindow& windowArg, const String& name, const String& version, const String& displayName, unsigned long estimatedSize, DatabaseCallback* creationCallback, ExceptionState& exceptionState)
 {
+    LocalDOMWindow& window = toLocalDOMWindow(windowArg);
     if (!window.isCurrentlyDisplayedInFrame())
         return nullptr;
 
     Database* database = nullptr;
     DatabaseManager& dbManager = DatabaseManager::manager();
     DatabaseError error = DatabaseError::None;
     if (RuntimeEnabledFeatures::databaseEnabled() && window.document()->securityOrigin()->canAccessDatabase()) {
         String errorMessage;
         database = dbManager.openDatabase(window.document(), name, version, displayName, estimatedSize, creationCallback, error, errorMessage);
         ASSERT(database || error != DatabaseError::None);
         if (error != DatabaseError::None)
             DatabaseManager::throwExceptionForDatabaseError(error, errorMessage, exceptionState);
     } else {
         exceptionState.throwSecurityError("Access to the WebDatabase API is denied in this context.");
     }
 
     return database;
 }
 
 } // namespace blink