Remove unused includes from core/{editing,fileapi,history,html}

Source/core/editing/EditingStyle.cpp

 /*
  * Copyright (C) 2007, 2008, 2009 Apple Computer, Inc.
  * Copyright (C) 2010, 2011 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 34 matching lines @@
 #include "core/dom/StyledElement.h"
 #include "core/editing/ApplyStyleCommand.h"
 #include "core/editing/Editor.h"
 #include "core/editing/FrameSelection.h"
 #include "core/editing/HTMLInterchange.h"
 #include "core/editing/htmlediting.h"
 #include "core/html/HTMLFontElement.h"
 #include "core/page/Frame.h"
 #include "core/page/RuntimeCSSEnabled.h"
 #include "core/rendering/style/RenderStyle.h"
-#include <wtf/HashSet.h>
 
 namespace WebCore {
 
 // Editing style properties must be preserved during editing operation.
 // e.g. when a user inserts a new paragraph, all properties listed here must be copied to the new paragraph.
 // NOTE: Use editingProperties() to respect runtime enabling of properties.
 static const unsigned nonInheritedStaticPropertiesCount = 2;
 
 static const CSSPropertyID staticEditingProperties[] = {
     // NOTE: inheritableEditingProperties depends on these two properties being first.
@@ skipping 1551 matching lines @@
 {
     for (Node* ancestor = node; ancestor; ancestor = ancestor->parentNode()) {
         RefPtr<CSSComputedStyleDeclaration> ancestorStyle = CSSComputedStyleDeclaration::create(ancestor);
         if (!hasTransparentBackgroundColor(ancestorStyle.get()))
             return ancestorStyle->getPropertyCSSValue(CSSPropertyBackgroundColor);
     }
     return 0;
 }
 
 }