Remove unused includes from various .cpp files in core/

Source/core/animation/DocumentTimeline.cpp

 /*
  * Copyright (C) 2013 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 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/animation/DocumentTimeline.h"
 
-#include "RuntimeEnabledFeatures.h"
 #include "core/animation/Player.h"
 #include "core/dom/Document.h"
 #include "core/page/FrameView.h"
 
 namespace WebCore {
 
 PassRefPtr<DocumentTimeline> DocumentTimeline::create(Document* document)
 {
     return adoptRef(new DocumentTimeline(document));
 }
@@ skipping 23 matching lines @@
     for (int i = m_players.size() - 1; i >= 0; --i) {
         if (!m_players[i]->update())
             m_players.remove(i);
     }
 
     if (m_document->view() && !m_players.isEmpty())
         m_document->view()->scheduleAnimation();
 }
 
 } // namespace