Disallow 'yield' in async arrow parameter lists inside generators

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 2879 matching lines @@
         Scanner::Location spread_pos;
         typename Traits::Type::ExpressionList args;
         if (V8_UNLIKELY(is_async && this->IsIdentifier(result))) {
           ExpressionClassifier async_classifier(this);
           args = ParseArguments(&spread_pos, true, &async_classifier, CHECK_OK);
           if (peek() == Token::ARROW) {
             if (fni_) {
               fni_->RemoveAsyncKeywordFromEnd();
             }
             ValidateBindingPattern(&async_classifier, CHECK_OK);
+            ValidateFormalParameterInitializer(&async_classifier, CHECK_OK);
             if (!async_classifier.is_valid_async_arrow_formal_parameters()) {
               ReportClassifierError(
                   async_classifier.async_arrow_formal_parameters_error());
               *ok = false;
               return this->EmptyExpression();
             }
             if (args->length()) {
               // async ( Arguments ) => ...
               return Traits::ExpressionListToExpression(args);
             }
@@ skipping 814 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H