Remove always-on --harmony-rest-parameters flag

src/parsing/parser.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_PARSING_PARSER_H_
 #define V8_PARSING_PARSER_H_
 
 #include "src/allocation.h"
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
@@ skipping 1374 matching lines @@
 }
 
 
 void ParserTraits::AddFormalParameter(ParserFormalParameters* parameters,
                                       Expression* pattern,
                                       Expression* initializer,
                                       int initializer_end_position,
                                       bool is_rest) {
   bool is_simple =
       !is_rest && pattern->IsVariableProxy() && initializer == nullptr;
-  DCHECK(parser_->allow_harmony_destructuring_bind() ||
-         parser_->allow_harmony_rest_parameters() ||
-         parser_->allow_harmony_default_parameters() || is_simple);
   const AstRawString* name = is_simple
                                  ? pattern->AsVariableProxy()->raw_name()
                                  : parser_->ast_value_factory()->empty_string();
   parameters->params.Add(
       ParserFormalParameters::Parameter(name, pattern, initializer,
                                         initializer_end_position, is_rest),
       parameters->scope->zone());
 }
 
 
@@ skipping 37 matching lines @@
 
 DoExpression* ParserTraits::ParseDoExpression(bool* ok) {
   return parser_->ParseDoExpression(ok);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_H_