[parser] improve inferred function names for async arrow functions

src/parsing/parser-base.h

Index: src/parsing/parser-base.h
diff --git a/src/parsing/parser-base.h b/src/parsing/parser-base.h
index c7e4daf97c2b555056c1e17d9d7d78d09df19f0f..33975e86c661c734128ff4f9348b048028619810 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -2322,11 +2322,17 @@ ParserBase<Traits>::ParseAssignmentExpression(bool accept_IN,
   }
 
   if (is_async && peek_any_identifier() && PeekAhead() == Token::ARROW) {
-    // async Identifier => AsyncConciseBody
-    IdentifierT name =
-        ParseAndClassifyIdentifier(&arrow_formals_classifier, CHECK_OK);
-    expression = this->ExpressionFromIdentifier(name, position(),
-                                                scanner()->location().end_pos);
+    if (this->IsIdentifier(expression)) {
+      // async Identifier => AsyncConciseBody
+      IdentifierT name =
+          ParseAndClassifyIdentifier(&arrow_formals_classifier, CHECK_OK);
+      expression = this->ExpressionFromIdentifier(
+          name, position(), scanner()->location().end_pos, InferName::No);
+      if (fni_) {
+        // Remove `async` keyword from inferred name stack.
+        fni_->RemoveAsyncKeywordFromEnd();
+      }
+    }
   }
 
   if (peek() == Token::ARROW) {
@@ -2882,10 +2888,13 @@ ParserBase<Traits>::ParseLeftHandSideExpression(
         }
         Scanner::Location spread_pos;
         typename Traits::Type::ExpressionList args;
-        if (V8_UNLIKELY(is_async)) {
+        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);
             if (!async_classifier.is_valid_async_arrow_formal_parameters()) {
               ReportClassifierError(