[parser] don't report error for CoverInitializedNames 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 2142 matching lines @@
   bool was_unspread = false;
   int unspread_sequences_count = 0;
   while (!done) {
     int start_pos = peek_position();
     bool is_spread = Check(Token::ELLIPSIS);
     int expr_pos = peek_position();
 
     ExpressionT argument = this->ParseAssignmentExpression(
         true, classifier, CHECK_OK_CUSTOM(NullExpressionList));
     CheckNoTailCallExpressions(classifier, CHECK_OK_CUSTOM(NullExpressionList));
-    Traits::RewriteNonPattern(classifier, CHECK_OK_CUSTOM(NullExpressionList));
+    if (!maybe_arrow) {
+      Traits::RewriteNonPattern(classifier,
+                                CHECK_OK_CUSTOM(NullExpressionList));
+    }
     if (is_spread) {
       if (!spread_arg.IsValid()) {
         spread_arg.beg_pos = start_pos;
         spread_arg.end_pos = peek_position();
       }
       argument = factory()->NewSpread(argument, start_pos, expr_pos);
     }
     result->Add(argument, zone_);
 
     // unspread_sequences_count is the number of sequences of parameters which
@@ skipping 16 matching lines @@
     }
   }
   Scanner::Location location = scanner_->location();
   if (Token::RPAREN != Next()) {
     ReportMessageAt(location, MessageTemplate::kUnterminatedArgList);
     *ok = false;
     return this->NullExpressionList();
   }
   *first_spread_arg_loc = spread_arg;
 
-  if ((!maybe_arrow || peek() != Token::ARROW) && spread_arg.IsValid()) {
-    // Unspread parameter sequences are translated into array literals in the
-    // parser. Ensure that the number of materialized literals matches between
-    // the parser and preparser
-    Traits::MaterializeUnspreadArgumentsLiterals(unspread_sequences_count);
+  if (!maybe_arrow || peek() != Token::ARROW) {
+    if (maybe_arrow) {
+      Traits::RewriteNonPattern(classifier,
+                                CHECK_OK_CUSTOM(NullExpressionList));
+    }
+    if (spread_arg.IsValid()) {
+      // Unspread parameter sequences are translated into array literals in the
+      // parser. Ensure that the number of materialized literals matches between
+      // the parser and preparser
+      Traits::MaterializeUnspreadArgumentsLiterals(unspread_sequences_count);
+    }
   }
 
   return result;
 }
 
 // Precedence = 2
 template <class Traits>
 typename ParserBase<Traits>::ExpressionT
 ParserBase<Traits>::ParseAssignmentExpression(bool accept_IN,
                                               ExpressionClassifier* classifier,
@@ skipping 1406 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H