Introduce ModuleScope subclass of DeclarationScope

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-containers.h"
@@ skipping 46 matching lines @@
     const AstRawString* module_request, const Scanner::Location loc,
     Zone* zone);
 
   // export * from "foo.js";
   void AddStarExport(
     const AstRawString* module_request, const Scanner::Location loc,
     Zone* zone);
 
   // Check if module is well-formed and report error if not.
   // Also canonicalize indirect exports.
-  bool Validate(DeclarationScope* module_scope,
+  bool Validate(ModuleScope* module_scope,
                 PendingCompilationErrorHandler* error_handler, Zone* zone);
 
   struct ModuleEntry : public ZoneObject {
     const Scanner::Location location;
     const AstRawString* export_name;
     const AstRawString* local_name;
     const AstRawString* import_name;
     const AstRawString* module_request;
 
     explicit ModuleEntry(Scanner::Location loc)
@@ skipping 38 matching lines @@
   // into:
   //   import {a as b} from "X"; export {a as c} from "X";
   // (The import entry is never deleted.)
   void MakeIndirectExportsExplicit();
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_MODULES_H_