CSS Tokenizer: Add an on-stack tokenizer scope

Source/core/css/parser/SizesAttributeParser.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SizesAttributeParser_h
 #define SizesAttributeParser_h
 
 #include "core/css/MediaValues.h"
 #include "core/css/parser/MediaQueryBlockWatcher.h"
 #include "core/css/parser/MediaQueryParser.h"
 #include "platform/heap/Handle.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class SizesAttributeParser {
     STACK_ALLOCATED();
 public:
     SizesAttributeParser(PassRefPtr<MediaValues>, const String&);
 
     float length();
 
 private:
-    bool parse(Vector<CSSParserToken>& tokens);
+    bool parse(CSSParserTokenRange);
     float effectiveSize();
     bool calculateLengthInPixels(CSSParserTokenRange, float& result);
     bool mediaConditionMatches(PassRefPtrWillBeRawPtr<MediaQuerySet> mediaCondition);
     unsigned effectiveSizeDefaultValue();
 
     RefPtrWillBeMember<MediaQuerySet> m_mediaCondition;
     RefPtr<MediaValues> m_mediaValues;
     float m_length;
     bool m_lengthWasSet;
-    Vector<CSSParserToken> m_tokens;
     bool m_isValid;
 };
 
 } // namespace
 
 #endif