Unprefix the @viewport rule of CSS Device Adaptation spec

Source/core/css/CSSViewportRule.cpp

 /*
  * Copyright (C) 2012 Intel Corporation. All rights reserved.
  * Copyright (C) 2012 Apple 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
@@ skipping 44 matching lines @@
 {
     if (!m_propertiesCSSOMWrapper)
         m_propertiesCSSOMWrapper = StyleRuleCSSStyleDeclaration::create(m_viewportRule->mutableProperties(), const_cast<CSSViewportRule*>(this));
 
     return m_propertiesCSSOMWrapper.get();
 }
 
 String CSSViewportRule::cssText() const
 {
     StringBuilder result;
-    result.appendLiteral("@-webkit-viewport { ");
+    result.appendLiteral("@viewport { ");
 
     String decls = m_viewportRule->properties()->asText();
     result.append(decls);
     if (!decls.isEmpty())
         result.append(' ');
 
     result.append('}');
 
     return result.toString();
 }
@@ skipping 10 matching lines @@
 
 void CSSViewportRule::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
 {
     MemoryClassInfo info(memoryObjectInfo, this, WebCoreMemoryTypes::CSS);
     CSSRule::reportMemoryUsage(memoryObjectInfo);
     info.addMember(m_viewportRule, "viewportRule");
     info.addMember(m_propertiesCSSOMWrapper, "propertiesCSSOMWrapper");
 }
 
 } // namespace WebCore