Implement parsing of ES6 Rest Parameters

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 457 matching lines @@
   // Checking the parameter names of a function literal. This has to be done
   // after parsing the function, since the function can declare itself strict.
   void CheckFunctionParameterNames(LanguageMode language_mode,
                                    bool strict_params,
                                    const Scanner::Location& eval_args_error_loc,
                                    const Scanner::Location& dupe_error_loc,
                                    const Scanner::Location& reserved_loc,
                                    bool* ok) {
     if (is_sloppy(language_mode) && !strict_params) return;
 
-    if (eval_args_error_loc.IsValid()) {
+    if (is_strict(language_mode) && eval_args_error_loc.IsValid()) {
       Traits::ReportMessageAt(eval_args_error_loc, "strict_eval_arguments");
       *ok = false;
       return;
     }
     // TODO(arv): When we add support for destructuring in setters we also need
     // to check for duplicate names.
     if (dupe_error_loc.IsValid()) {
       Traits::ReportMessageAt(dupe_error_loc, "strict_param_dupe");
       *ok = false;
       return;
@@ skipping 2587 matching lines @@
       *ok = false;
       return;
     }
     has_seen_constructor_ = true;
     return;
   }
 }
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H