Split NewScope into NewScope and NewScopeWithParent

src/parsing/parser-base.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_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
 #include "src/base/hashmap.h"
@@ skipping 601 matching lines @@
 
    private:
     ParserBase* parser_;
     Mode old_mode_;
   };
 
   Scope* NewScriptScope() {
     return new (zone()) Scope(zone(), nullptr, SCRIPT_SCOPE, kNormalFunction);
   }
 
-  Scope* NewScope(Scope* parent, ScopeType scope_type) {
+  Scope* NewScope(ScopeType scope_type) {
+    return NewScopeWithParent(scope(), scope_type);
+  }
+
+  // This constructor should only be used when absolutely necessary. Most scopes
+  // should automatically use scope() as parent, and be fine with
+  // NewScope(ScopeType) above.
+  Scope* NewScopeWithParent(Scope* parent, ScopeType scope_type) {
     // Must always use the specific constructors for the blacklisted scope
     // types.
     DCHECK_NE(FUNCTION_SCOPE, scope_type);
     DCHECK_NE(SCRIPT_SCOPE, scope_type);
     DCHECK_NOT_NULL(parent);
     Scope* result =
         new (zone()) Scope(zone(), parent, scope_type, kNormalFunction);
     if (scope_type == MODULE_SCOPE) result->DeclareThis(ast_value_factory());
     return result;
   }
@@ skipping 3056 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H