Fix compile-problem in (currently) unused stand-alone preparser function.

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index 893b575198bf0cf0cdd775d458ca310d1cddae76..536e6d4f431050037970bd725126f8e9569a48eb 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -216,8 +216,11 @@ class PreParser {
   Identifier ParseIdentifierName(bool* ok);
   Identifier ParseIdentifierOrGetOrSet(bool* is_get, bool* is_set, bool* ok);
 
+  // Logs the currently parsed literal as a symbol in the preparser data.
+  void LogSymbol();
+  // Log the currently parsed identifier.
   Identifier GetIdentifierSymbol();
-  unsigned int HexDigitValue(char digit);
+  // Log the currently parsed string literal.
   Expression GetStringSymbol();
 
   i::Token::Value peek() {