Remove synthetic unresolved variables from async/await desugaring

src/parsing/preparser.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_PREPARSER_H
 #define V8_PARSING_PREPARSER_H
 
 #include "src/ast/scopes.h"
 #include "src/parsing/parser-base.h"
 
@@ skipping 687 matching lines @@
  public:
   explicit PreParserTargetScope(ParserBase<PreParser>* preparser) {}
 };
 
 template <>
 struct ParserTypes<PreParser> {
   typedef ParserBase<PreParser> Base;
   typedef PreParser Impl;
 
   // PreParser doesn't need to store generator variables.
-  typedef void GeneratorVariable;
+  typedef void Variable;
 
   // Return types for traversing functions.
   typedef PreParserIdentifier Identifier;
   typedef PreParserExpression Expression;
   typedef PreParserExpression FunctionLiteral;
   typedef PreParserExpression ObjectLiteralProperty;
   typedef PreParserExpression ClassLiteralProperty;
   typedef PreParserExpressionList ExpressionList;
   typedef PreParserExpressionList PropertyList;
   typedef PreParserFormalParameters FormalParameters;
@@ skipping 697 matching lines @@
     function_state_->NextMaterializedLiteralIndex();
     function_state_->NextMaterializedLiteralIndex();
   }
   return EmptyExpression();
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PREPARSER_H