Remove unused includes from various .cpp files in core/

Source/core/editing/SurroundingText.cpp

 /*
  * Copyright (C) 2012 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 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/editing/SurroundingText.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/Range.h"
 #include "core/editing/TextIterator.h"
 #include "core/editing/VisiblePosition.h"
-#include "core/editing/VisibleSelection.h"
 #include "core/editing/VisibleUnits.h"
 
 namespace WebCore {
 
 SurroundingText::SurroundingText(const VisiblePosition& visiblePosition, unsigned maxLength)
     : m_positionOffsetInContent(0)
 {
     if (visiblePosition.isNull())
         return;
 
@@ skipping 53 matching lines @@
         return m_contentRange->text();
     return String();
 }
 
 unsigned SurroundingText::positionOffsetInContent() const
 {
     return m_positionOffsetInContent;
 }
 
 } // namespace WebCore