[modules] Do basic linking.

src/ast/modules.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_AST_MODULES_H_
 #define V8_AST_MODULES_H_
 
 #include "src/parsing/scanner.h"  // Only for Scanner::Location.
 #include "src/pending-compilation-error-handler.h"
 #include "src/zone/zone-containers.h"
@@ skipping 118 matching lines @@
 
   void AddRegularExport(Entry* entry) {
     DCHECK_NOT_NULL(entry->export_name);
     DCHECK_NOT_NULL(entry->local_name);
     DCHECK_NULL(entry->import_name);
     DCHECK_LT(entry->module_request, 0);
     regular_exports_.insert(std::make_pair(entry->local_name, entry));
   }
 
   void AddSpecialExport(const Entry* entry, Zone* zone) {
+    DCHECK_NULL(entry->local_name);
     DCHECK_LE(0, entry->module_request);
     special_exports_.Add(entry, zone);
   }
 
   void AddRegularImport(const Entry* entry) {
     DCHECK_NOT_NULL(entry->import_name);
     DCHECK_NOT_NULL(entry->local_name);
     DCHECK_NULL(entry->export_name);
     DCHECK_LE(0, entry->module_request);
     regular_imports_.insert(std::make_pair(entry->local_name, entry));
@@ skipping 48 matching lines @@
                   .insert(std::make_pair(specifier, module_requests_.size()))
                   .first;
     return it->second;
   }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_MODULES_H_