Use CSSTokenizerInputStream::peekWithoutReplacement instead of peek().

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:
     explicit CSSTokenizerInputStream(String input);
 
-    UChar peek(unsigned) const;
-    UChar nextInputChar() const { return peek(0); }
+    // Gets the char in the stream replacing NUL characters with a unicode
+    // replacement character. Will return (NUL) kEndOfFileMarker when at the
+    // end of the stream.
+    UChar nextInputChar() const
+    {
+        if (m_offset >= m_stringLength)
+            return '\0';
+        UChar result = (*m_string)[m_offset];
+        return result ? result : 0xFFFD;
+    }
 
-    // For fast-path code, don't replace nulls with replacement characters
+    // Gets the char at lookaheadOffset from the current stream position. Will
+    // return NUL (kEndOfFileMarker) if the stream position is at the end.
+    // NOTE: This may *also* return NUL if there's one in the input! Never
+    // compare the return value to '\0'.
     UChar peekWithoutReplacement(unsigned lookaheadOffset) const
     {
-        DCHECK((m_offset + lookaheadOffset) <= m_stringLength);
-        if ((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 cc)
     {
         --m_offset;
         DCHECK(nextInputChar() == cc);
     }
@@ skipping 17 matching lines @@
 private:
     size_t m_offset;
     const size_t m_stringLength;
     const RefPtr<StringImpl> m_string;
 };
 
 } // namespace blink
 
 #endif // CSSTokenizerInputStream_h