Remove GamePad runtime flag(status=stable)

Source/web/FrameLoaderClientImpl.cpp

 /*
  * Copyright (C) 2009, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple 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.
@@ skipping 98 matching lines @@
 }
 
 void FrameLoaderClientImpl::dispatchDidClearWindowObjectInMainWorld()
 {
     if (m_webFrame->client()) {
         m_webFrame->client()->didClearWindowObject(m_webFrame);
         Document* document = m_webFrame->frame()->document();
         if (document) {
             DeviceMotionController::from(*document);
             DeviceOrientationController::from(*document);
+            NavigatorGamepad::from(*document);
             if (RuntimeEnabledFeatures::deviceLightEnabled())
                 DeviceLightController::from(*document);
-            if (RuntimeEnabledFeatures::gamepadEnabled())
-                NavigatorGamepad::from(*document);
             if (RuntimeEnabledFeatures::serviceWorkerEnabled())
                 NavigatorServiceWorker::from(*document);
         }
     }
 }
 
 void FrameLoaderClientImpl::documentElementAvailable()
 {
     if (m_webFrame->client())
         m_webFrame->client()->didCreateDocumentElement(m_webFrame);
@@ skipping 699 matching lines @@
         m_webFrame->client()->didAbortLoading(m_webFrame);
 }
 
 void FrameLoaderClientImpl::dispatchDidChangeManifest()
 {
     if (m_webFrame->client())
         m_webFrame->client()->didChangeManifest(m_webFrame);
 }
 
 } // namespace blink