Remove unnecessary Document.h includes in .cpp files

Source/modules/push_messaging/NavigatorPushManager.cpp

 // Copyright 2014 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 "config.h"
 #include "modules/push_messaging/NavigatorPushManager.h"
 
-#include "core/dom/Document.h"
 #include "core/frame/Navigator.h"
 #include "modules/push_messaging/PushManager.h"
 
 namespace WebCore {
 
 NavigatorPushManager::NavigatorPushManager()
 {
 }
 
 NavigatorPushManager::~NavigatorPushManager()
@@ skipping 27 matching lines @@
     return m_pushManager.get();
 }
 
 void NavigatorPushManager::trace(Visitor* visitor)
 {
     visitor->trace(m_pushManager);
     WillBeHeapSupplement<Navigator>::trace(visitor);
 }
 
 } // namespace WebCore