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 293 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 = CSSValueExtendToZoom;
+            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 1011 matching lines @@
         break;
     case CSS_CALC:
         info.addMember(m_value.calc, "value.calc");
         break;
     default:
         break;
     }
 }
 
 } // namespace WebCore