[ast cleanup] Remove unnecessary frozen_ bit from ModuleDescriptor

src/ast/modules.cc

 // 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.
 
 #include "src/ast/modules.h"
 
 #include "src/ast/ast-value-factory.h"
 
 namespace v8 {
 namespace internal {
 
 
 void ModuleDescriptor::AddLocalExport(const AstRawString* export_name,
                                       const AstRawString* local_name,
                                       Zone* zone, bool* ok) {
-  DCHECK(!IsFrozen());
   void* key = const_cast<AstRawString*>(export_name);
 
   ZoneAllocationPolicy allocator(zone);
 
   if (exports_ == nullptr) {
     exports_ = new (zone->New(sizeof(ZoneHashMap)))
         ZoneHashMap(ZoneHashMap::PointersMatch,
                     ZoneHashMap::kDefaultHashMapCapacity, allocator);
   }
 
@@ skipping 23 matching lines @@
     const AstRawString* export_name, Zone* zone) {
   if (exports_ == nullptr) return nullptr;
   ZoneHashMap::Entry* entry = exports_->Lookup(
       const_cast<AstRawString*>(export_name), export_name->hash());
   if (entry == nullptr) return nullptr;
   DCHECK_NOT_NULL(entry->value);
   return static_cast<const AstRawString*>(entry->value);
 }
 }  // namespace internal
 }  // namespace v8