Fix serialization of alias_for properties

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 241 matching lines @@
     case CalcTime:
         return CSS_MS;
     case CalcOther:
         return CSS_UNKNOWN;
     }
     return CSS_UNKNOWN;
 }
 
 static const AtomicString& propertyName(CSSPropertyID propertyID)
 {
-    ASSERT_ARG(propertyID, propertyID >= 0);
-    ASSERT_ARG(propertyID, (propertyID >= firstCSSProperty && propertyID < firstCSSProperty + numCSSProperties));
-
-    if (propertyID < 0)
-        return nullAtom;
-
     return getPropertyNameAtomicString(propertyID);
 }
 
 static const AtomicString& valueName(CSSValueID valueID)
 {
     ASSERT_ARG(valueID, valueID >= 0);
     ASSERT_ARG(valueID, valueID < numCSSValueKeywords);
 
     if (valueID < 0)
         return nullAtom;
@@ skipping 946 matching lines @@
         visitor->trace(m_value.shape);
         break;
     default:
         break;
     }
 #endif
     CSSValue::traceAfterDispatch(visitor);
 }
 
 } // namespace blink