[parser] report error for shorthand property "await" in async arrow formals

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 1928 matching lines @@
       // CoverInitializedName
       //    IdentifierReference Initializer?
       if (classifier->duplicate_finder() != nullptr &&
           scanner()->FindSymbol(classifier->duplicate_finder(), 1) != 0) {
         classifier->RecordDuplicateFormalParameterError(scanner()->location());
       }
       if (name_token == Token::LET) {
         classifier->RecordLetPatternError(
             scanner()->location(), MessageTemplate::kLetInLexicalBinding);
       }
-      if (is_await && is_async_function()) {
-        classifier->RecordPatternError(
-            Scanner::Location(next_beg_pos, next_end_pos),
-            MessageTemplate::kAwaitBindingIdentifier);
+      if (is_await) {
+        if (is_async_function()) {
+          classifier->RecordPatternError(
+              Scanner::Location(next_beg_pos, next_end_pos),
+              MessageTemplate::kAwaitBindingIdentifier);
+        } else {
+          classifier->RecordAsyncArrowFormalParametersError(
+              Scanner::Location(next_beg_pos, next_end_pos),
+              MessageTemplate::kAwaitBindingIdentifier);
+        }
       }
       ExpressionT lhs = this->ExpressionFromIdentifier(
           *name, next_beg_pos, next_end_pos, scope_, factory());
       CheckDestructuringElement(lhs, classifier, next_beg_pos, next_end_pos);
 
       if (peek() == Token::ASSIGN) {
         Consume(Token::ASSIGN);
         ExpressionClassifier rhs_classifier(this);
         ExpressionT rhs = this->ParseAssignmentExpression(
             true, &rhs_classifier, CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
@@ skipping 1667 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H