[es6] emit error when for-in loop declarations are initialized in strict mode

src/preparser.h

 // Copyright 2012 the V8 project 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 V8_PREPARSER_H
 #define V8_PREPARSER_H
 
 #include "src/v8.h"
 
 #include "src/bailout-reason.h"
@@ skipping 1572 matching lines @@
   Statement ParseStatement(bool* ok);
   Statement ParseSubStatement(bool* ok);
   Statement ParseFunctionDeclaration(bool* ok);
   Statement ParseClassDeclaration(bool* ok);
   Statement ParseBlock(bool* ok);
   Statement ParseVariableStatement(VariableDeclarationContext var_context,
                                    bool* ok);
   Statement ParseVariableDeclarations(VariableDeclarationContext var_context,
                                       VariableDeclarationProperties* decl_props,
                                       int* num_decl,
+                                      Scanner::Location* first_initializer_loc,
                                       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);
@@ skipping 1554 matching lines @@
       *ok = false;
       return;
     }
     has_seen_constructor_ = true;
     return;
   }
 }
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H