No need to store invalid media queries.

Source/core/css/MediaQueryExp.h

 /*
  * CSS Media Query
  *
  * Copyright (C) 2006 Kimmo Kinnunen <kimmo.t.kinnunen@nokia.com>.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * 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
@@ skipping 23 matching lines @@
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefPtr.h"
 #include "wtf/text/AtomicString.h"
 
 namespace WebCore {
 class CSSParserValueList;
 
 class MediaQueryExp {
     WTF_MAKE_FAST_ALLOCATED;
 public:
-    static PassOwnPtr<MediaQueryExp> create(const AtomicString& mediaFeature, CSSParserValueList* values);
+    static PassOwnPtr<MediaQueryExp> create(const AtomicString& mediaFeature, CSSParserValueList*);
     ~MediaQueryExp();
 
     AtomicString mediaFeature() const { return m_mediaFeature; }
 
     CSSValue* value() const { return m_value.get(); }
 
     bool operator==(const MediaQueryExp& other) const
     {
         return (other.m_mediaFeature == m_mediaFeature)
             && ((!other.m_value && !m_value)
                 || (other.m_value && m_value && other.m_value->equals(*m_value)));
     }
 
-    bool isValid() const { return m_isValid; }
-
     bool isViewportDependent() const;
 
     String serialize() const;
 
     PassOwnPtr<MediaQueryExp> copy() const { return adoptPtr(new MediaQueryExp(*this)); }
 
     void reportMemoryUsage(MemoryObjectInfo*) const;
 
 private:
-    MediaQueryExp(const AtomicString& mediaFeature, CSSParserValueList* values);
+    MediaQueryExp(const AtomicString& mediaFeature, PassRefPtr<CSSValue>);
 
     AtomicString m_mediaFeature;
     RefPtr<CSSValue> m_value;
-    bool m_isValid;
 };
 
 } // namespace
 
 #endif