Move the CSS Device Adaptation @viewport rule support behind a runtime flag

Source/core/css/StyleSheetContents.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 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 439 matching lines @@
                 return true;
             break;
         case StyleRuleBase::Import:
             ASSERT_NOT_REACHED();
         case StyleRuleBase::Page:
         case StyleRuleBase::Keyframes:
         case StyleRuleBase::Unknown:
         case StyleRuleBase::Charset:
         case StyleRuleBase::Keyframe:
         case StyleRuleBase::Supports:
-#if ENABLE(CSS_DEVICE_ADAPTATION)
         case StyleRuleBase::Viewport:
-#endif
         case StyleRuleBase::Filter:
             break;
         }
     }
     return false;
 }
 
 bool StyleSheetContents::hasFailedOrCanceledSubresources() const
 {
     ASSERT(isCacheable());
@@ skipping 45 matching lines @@
     info.addMember(m_originalURL, "originalURL");
     info.addMember(m_encodingFromCharsetRule, "encodingFromCharsetRule");
     info.addMember(m_importRules, "importRules");
     info.addMember(m_childRules, "childRules");
     info.addMember(m_namespaces, "namespaces");
     info.addMember(m_parserContext, "parserContext");
     info.addMember(m_clients, "clients");
 }
 
 }