Avoid copying strings when parsing CSS colors on the slow path.

third_party/WebKit/Source/core/css/parser/CSSTokenizerInputStream.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 CSSTokenizerInputStream_h
 #define CSSTokenizerInputStream_h
 
 #include "wtf/text/StringView.h"
 #include "wtf/text/WTFString.h"
 
@@ skipping 26 matching lines @@
     double getDouble(unsigned start, unsigned end);
 
     template<bool characterPredicate(UChar)>
     unsigned skipWhilePredicate(unsigned offset)
     {
         while ((m_offset + offset) < m_stringLength && characterPredicate((*m_string)[m_offset + offset]))
             ++offset;
         return offset;
     }
 
+    unsigned length() const { return m_stringLength; }
     unsigned offset() const { return std::min(m_offset, m_stringLength); }
     StringView rangeAt(unsigned start, unsigned length) const;
 
 private:
     size_t m_offset;
     const size_t m_stringLength;
     const RefPtr<StringImpl> m_string;
 };
 
 } // namespace blink
 
 #endif // CSSTokenizerInputStream_h