Add a setting to disable threaded scrolling

Source/web/WebSettingsImpl.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 383 matching lines @@
 void WebSettingsImpl::setAllowUniversalAccessFromFileURLs(bool allow)
 {
     m_settings->setAllowUniversalAccessFromFileURLs(allow);
 }
 
 void WebSettingsImpl::setAllowFileAccessFromFileURLs(bool allow)
 {
     m_settings->setAllowFileAccessFromFileURLs(allow);
 }
 
+void WebSettingsImpl::setThreadedScrollingEnabled(bool enabled)
+{
+    m_settings->setThreadedScrollingEnabled(enabled);
+}
+
 void WebSettingsImpl::setTouchDragDropEnabled(bool enabled)
 {
     m_settings->setTouchDragDropEnabled(enabled);
 }
 
 void WebSettingsImpl::setTouchEditingEnabled(bool enabled)
 {
     m_settings->setTouchEditingEnabled(enabled);
 }
 
@@ skipping 312 matching lines @@
 {
     m_settings->setV8CacheOptions(static_cast<blink::V8CacheOptions>(options));
 }
 
 void WebSettingsImpl::setV8ScriptStreamingEnabled(bool enabled)
 {
     m_settings->setV8ScriptStreamingEnabled(enabled);
 }
 
 } // namespace blink