[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 194 matching lines @@
     VariableProxy* proxy = initialization_scope->NewUnresolved(factory(), name);
     Assignment* assignment = factory()->NewAssignment(
         descriptor_->init_op, proxy, value, descriptor_->initialization_pos);
     block_->AddStatement(
         factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition),
         zone());
   }
 }
 
 
+void Parser::PatternRewriter::VisitRestParameter(RestParameter* node) {
+  // Rest parameter rewriting handled specially in the parser, but must still
+  // be declared.
+  DCHECK_EQ(DeclarationDescriptor::PARAMETER, descriptor_->declaration_kind);
+  VisitVariableProxy(node->parameter());
+}
+
+
 Variable* Parser::PatternRewriter::CreateTempVar(Expression* value) {
   auto temp = descriptor_->parser->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),
@@ skipping 193 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