Introduce ModuleScope subclass of DeclarationScope

src/parsing/parser.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/parsing/parser.h"
 
 #include <memory>
 
 #include "src/api.h"
 #include "src/ast/ast.h"
@@ skipping 986 matching lines @@
       info->script_scope()->DeclareDynamicGlobal(
           ast_value_factory()->this_string(), Variable::THIS);
     }
     DCHECK(outer);
     if (info->is_eval()) {
       if (!outer->is_script_scope() || is_strict(info->language_mode())) {
         parsing_mode = PARSE_EAGERLY;
       }
       outer = NewEvalScope(outer);
     } else if (info->is_module()) {
-      outer = NewModuleScope(outer);
+      DCHECK_EQ(outer, info->script_scope());
+      outer = NewModuleScope(info->script_scope());
     }
 
     DeclarationScope* scope = outer->AsDeclarationScope();
 
     scope->set_start_position(0);
 
     // Enter 'scope' with the given parsing mode.
     ParsingModeScope parsing_mode_scope(this, parsing_mode);
     FunctionState function_state(&function_state_, &scope_state_, scope,
                                  kNormalFunction);
 
     ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(16, zone());
     bool ok = true;
     int beg_pos = scanner()->location().beg_pos;
     parsing_module_ = info->is_module();
     if (parsing_module_) {
       ParseModuleItemList(body, &ok);
       ok = ok &&
-           module()->Validate(this->scope()->AsDeclarationScope(),
+           module()->Validate(this->scope()->AsModuleScope(),
                               &pending_error_handler_, zone());
     } else {
       // Don't count the mode in the use counters--give the program a chance
       // to enable script-wide strict mode below.
       this->scope()->SetLanguageMode(info->language_mode());
       ParseStatementList(body, Token::EOS, &ok);
     }
 
     // The parser will peek but not consume EOS.  Our scope logically goes all
     // the way to the EOS, though.
@@ skipping 6050 matching lines @@
   node->Print(Isolate::Current());
 }
 #endif  // DEBUG
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8