Add Settings::deviceScaleAdjustment.

Source/core/dom/ViewportDescription.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2012-2013 Intel Corporation. All rights reserved.
  *
@@ skipping 88 matching lines @@
             && deprecatedTargetDensityDPI == other.deprecatedTargetDensityDPI;
     }
 
     bool operator!=(const ViewportDescription& other) const
     {
         return !(*this == other);
     }
 
     bool isLegacyViewportType() const { return type >= HandheldFriendlyMeta && type <= ViewportMeta; }
     bool isMetaViewportType() const { return type == ViewportMeta; }
+    bool isSpecifiedByAuthor() const { return type != UserAgentStyleSheet; }
 
 private:
     enum Direction { Horizontal, Vertical };
     static float resolveViewportLength(const Length&, const FloatSize& initialViewportSize, Direction);
 };
 
 } // namespace WebCore
 
 #endif // ViewportDescription_h