Support 'extend-to-zoom' viewport descriptor value

Source/core/css/CSSPrimitiveValue.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2012 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 292 matching lines @@
             m_value.valueID = CSSValueMaxContent;
             break;
         case FillAvailable:
             m_primitiveUnitType = CSS_VALUE_ID;
             m_value.valueID = CSSValueWebkitFillAvailable;
             break;
         case FitContent:
             m_primitiveUnitType = CSS_VALUE_ID;
             m_value.valueID = CSSValueWebkitFitContent;
             break;
+        case ExtendToZoom:
+            m_primitiveUnitType = CSS_VALUE_ID;
+            m_value.valueID = CSSValueInternalExtendToZoom;
+            break;
         case Percent:
             m_primitiveUnitType = CSS_PERCENTAGE;
             ASSERT(std::isfinite(length.percent()));
             m_value.num = length.percent();
             break;
         case ViewportPercentageWidth:
             m_primitiveUnitType = CSS_VW;
             m_value.num = length.viewportPercentageLength();
             break;
         case ViewportPercentageHeight:
@@ skipping 974 matching lines @@
         return m_value.valueID == other.m_value.valueID;
     case CSS_CALC:
         return m_value.calc && other.m_value.calc && m_value.calc->equals(*other.m_value.calc);
     case CSS_SHAPE:
         return m_value.shape && other.m_value.shape && m_value.shape->equals(*other.m_value.shape);
     }
     return false;
 }
 
 } // namespace WebCore