Add missing const on CSSTokenizerInputStream methods.

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"
 
 namespace blink {
 
 class CSSTokenizerInputStream {
     WTF_MAKE_NONCOPYABLE(CSSTokenizerInputStream);
     USING_FAST_MALLOC(CSSTokenizerInputStream);
 public:
-    CSSTokenizerInputStream(String input);
+    explicit CSSTokenizerInputStream(String input);
 
-    UChar peek(unsigned);
-    inline UChar nextInputChar()
-    {
-        return peek(0);
-    }
+    UChar peek(unsigned) const;
+    UChar nextInputChar() const { return peek(0); }
 
     // For fast-path code, don't replace nulls with replacement characters
-    UChar peekWithoutReplacement(unsigned lookaheadOffset)
+    UChar peekWithoutReplacement(unsigned lookaheadOffset) const
     {
-        ASSERT((m_offset + lookaheadOffset) <= m_stringLength);
+        DCHECK((m_offset + lookaheadOffset) <= m_stringLength);
         if ((m_offset + lookaheadOffset) == m_stringLength)
             return '\0';
         return (*m_string)[m_offset + lookaheadOffset];
     }
 
     void advance(unsigned offset = 1) { m_offset += offset; }
-    void pushBack(UChar);
+    void pushBack(UChar cc)
+    {
+        --m_offset;
+        DCHECK(nextInputChar() == cc);
+    }
 
-    double getDouble(unsigned start, unsigned end);
+    double getDouble(unsigned start, unsigned end) const;
 
     template<bool characterPredicate(UChar)>
     unsigned skipWhilePredicate(unsigned offset)
     {
         while ((m_offset + offset) < m_stringLength && characterPredicate((*m_string)[m_offset + offset]))
             ++offset;
         return offset;
     }
 
     void advanceUntilNonWhitespace();
 
     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