[es6] re-implement rest parameters via desugaring

src/pattern-rewriter.cc

 // Copyright 2015 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.
 
 #include "src/ast.h"
 #include "src/messages.h"
 #include "src/parser.h"
 
 namespace v8 {
 
@@ skipping 196 matching lines @@
     Assignment* assignment = factory()->NewAssignment(
         descriptor_->init_op, proxy, value, descriptor_->initialization_pos);
     block_->AddStatement(
         factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition),
         zone());
   }
 }
 
 
 Variable* Parser::PatternRewriter::CreateTempVar(Expression* value) {
-  auto temp_scope = descriptor_->parser->scope_->DeclarationScope();
+  auto temp_scope = descriptor_->parser->scope_->TempScope();
   auto temp = temp_scope->NewTemporary(ast_value_factory()->empty_string());
   if (value != nullptr) {
     auto assignment = factory()->NewAssignment(
         Token::ASSIGN, factory()->NewVariableProxy(temp), value,
         RelocInfo::kNoPosition);
 
     block_->AddStatement(
         factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition),
         zone());
   }
@@ skipping 186 matching lines @@
 NOT_A_PATTERN(TryFinallyStatement)
 NOT_A_PATTERN(UnaryOperation)
 NOT_A_PATTERN(VariableDeclaration)
 NOT_A_PATTERN(WhileStatement)
 NOT_A_PATTERN(WithStatement)
 NOT_A_PATTERN(Yield)
 
 #undef NOT_A_PATTERN
 }  // namespace internal
 }  // namespace v8