Parse harmony let declarations.

src/preparser.h

 // Copyright 2011 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 359 matching lines @@
                        const char* name_opt) {
     log_->LogMessage(start_pos, end_pos, type, name_opt);
   }
 
   void CheckOctalLiteral(int beg_pos, int end_pos, bool* ok);
 
   // All ParseXXX functions take as the last argument an *ok parameter
   // which is set to false if parsing failed; it is unchanged otherwise.
   // By making the 'exception handling' explicit, we are forced to check
   // for failure at the call sites.
+  Statement ParseSourceElement(bool* ok);
   SourceElements ParseSourceElements(int end_token, bool* ok);
   Statement ParseStatement(bool* ok);
   Statement ParseFunctionDeclaration(bool* ok);
   Statement ParseBlock(bool* ok);
-  Statement ParseVariableStatement(bool* ok);
-  Statement ParseVariableDeclarations(bool accept_IN, int* num_decl, bool* ok);
+  Statement ParseVariableStatement(bool accept_LET, bool* ok);
+  Statement ParseVariableDeclarations(bool accept_LET, bool accept_IN,
+                                      int* num_decl, bool* ok);
   Statement ParseExpressionOrLabelledStatement(bool* ok);
   Statement ParseIfStatement(bool* ok);
   Statement ParseContinueStatement(bool* ok);
   Statement ParseBreakStatement(bool* ok);
   Statement ParseReturnStatement(bool* ok);
   Statement ParseWithStatement(bool* ok);
   Statement ParseSwitchStatement(bool* ok);
   Statement ParseDoWhileStatement(bool* ok);
   Statement ParseWhileStatement(bool* ok);
   Statement ParseForStatement(bool* ok);
@@ skipping 97 matching lines @@
   uintptr_t stack_limit_;
   i::Scanner::Location strict_mode_violation_location_;
   const char* strict_mode_violation_type_;
   bool stack_overflow_;
   bool allow_lazy_;
   bool parenthesized_function_;
 };
 } }  // v8::preparser
 
 #endif  // V8_PREPARSER_H