CSS Tokenizer: Add an on-stack tokenizer scope

Source/core/css/parser/SizesAttributeParser.cpp

Index: Source/core/css/parser/SizesAttributeParser.cpp
diff --git a/Source/core/css/parser/SizesAttributeParser.cpp b/Source/core/css/parser/SizesAttributeParser.cpp
index 68f601f2c52ae9160ab68f8c7315352b03afef7b..24881769af18ed9e61e853cd5e9d508a84f387b4 100644
--- a/Source/core/css/parser/SizesAttributeParser.cpp
+++ b/Source/core/css/parser/SizesAttributeParser.cpp
@@ -17,8 +17,7 @@ SizesAttributeParser::SizesAttributeParser(PassRefPtr<MediaValues> mediaValues,
     , m_length(0)
     , m_lengthWasSet(false)
 {
-    CSSTokenizer::tokenize(attribute, m_tokens);
-    m_isValid = parse(m_tokens);
+    m_isValid = parse(CSSTokenizer::Scope(attribute).tokenRange());
 }
 
 float SizesAttributeParser::length()
@@ -61,9 +60,8 @@ bool SizesAttributeParser::mediaConditionMatches(PassRefPtrWillBeRawPtr<MediaQue
     return mediaQueryEvaluator.eval(mediaCondition.get());
 }
 
-bool SizesAttributeParser::parse(Vector<CSSParserToken>& tokens)
+bool SizesAttributeParser::parse(CSSParserTokenRange range)
 {
-    CSSParserTokenRange range(tokens);
     // Split on a comma token and parse the result tokens as (media-condition, length) pairs
     while (!range.atEnd()) {
         const CSSParserToken* mediaConditionStart = &range.peek();