Separate JSON parsing from the JavaScript parser.

src/scanner.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 278 matching lines @@
   void Initialize(Handle<String> source,
                   unibrow::CharacterStream* stream,
                   ParserLanguage language);
   void Initialize(Handle<String> source,
                   int start_position, int end_position,
                   ParserLanguage language);
 
   // Returns the next token.
   Token::Value Next();
 
+  // Returns the current token again.
+  Token::Value current_token() { return current_.token; }
+
   // One token look-ahead (past the token returned by Next()).
   Token::Value peek() const { return next_.token; }
 
   // Returns true if there was a line terminator before the peek'ed token.
   bool has_line_terminator_before_next() const {
     return has_line_terminator_before_next_;
   }
 
   struct Location {
     Location(int b, int e) : beg_pos(b), end_pos(e) { }
@@ skipping 201 matching lines @@
   bool stack_overflow_;
   static StaticResource<Utf8Decoder> utf8_decoder_;
 
   // One Unicode character look-ahead; c0_ < 0 at the end of the input.
   uc32 c0_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_SCANNER_H_