[es6] conditionally ignore TDZ semantics for formals

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 35 matching lines @@
   // surrounding 'with' statements).
   // For let/const declarations in harmony mode, we can also immediately
   // pre-resolve the proxy because it resides in the same scope as the
   // declaration.
   Parser* parser = descriptor_->parser;
   const AstRawString* name = pattern->raw_name();
   VariableProxy* proxy = parser->NewUnresolved(name, descriptor_->mode);
   Declaration* declaration = factory()->NewVariableDeclaration(
       proxy, descriptor_->mode, descriptor_->scope,
       descriptor_->declaration_pos);
-  Variable* var = parser->Declare(declaration, descriptor_->declaration_kind,
-                                  descriptor_->mode != VAR, ok_,
-                                  descriptor_->hoist_scope);
+  Variable* var = parser->Declare(
+      declaration, descriptor_->declaration_kind,
+      descriptor_->declaration_kind == DeclarationDescriptor::PARAMETER ||
+          descriptor_->mode != VAR,
+      ok_, descriptor_->hoist_scope);
   if (!*ok_) return;
   DCHECK_NOT_NULL(var);
   DCHECK(!proxy->is_resolved() || proxy->var() == var);
   var->set_initializer_position(initializer_position_);
 
   DCHECK(initializer_position_ != RelocInfo::kNoPosition);
 
   if (descriptor_->declaration_scope->num_var_or_const() >
       kMaxNumFunctionLocals) {
     parser->ReportMessage(MessageTemplate::kTooManyVariables);
@@ skipping 349 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