[parser] improve inferred function names for async arrow functions

src/parsing/func-name-inferrer.cc

 // Copyright 2011 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.
 
 #include "src/parsing/func-name-inferrer.h"
 
 #include "src/ast/ast.h"
 #include "src/ast/ast-value-factory.h"
 #include "src/list-inl.h"
 
@@ skipping 26 matching lines @@
   }
 }
 
 
 void FuncNameInferrer::PushVariableName(const AstRawString* name) {
   if (IsOpen() && name != ast_value_factory_->dot_result_string()) {
     names_stack_.Add(Name(name, kVariableName), zone());
   }
 }
 
+void FuncNameInferrer::RemoveAsyncKeywordFromEnd() {
+  DCHECK(names_stack_.length() > 0);
+  DCHECK(names_stack_.last().name->IsOneByteEqualTo("async"));
+  names_stack_.RemoveLast();
+}
 
 const AstString* FuncNameInferrer::MakeNameFromStack() {
   return MakeNameFromStackHelper(0, ast_value_factory_->empty_string());
 }
 
 const AstString* FuncNameInferrer::MakeNameFromStackHelper(
     int pos, const AstString* prev) {
   if (pos >= names_stack_.length()) return prev;
   if (pos < names_stack_.length() - 1 &&
       names_stack_.at(pos).type == kVariableName &&
@@ skipping 19 matching lines @@
   const AstString* func_name = MakeNameFromStack();
   for (int i = 0; i < funcs_to_infer_.length(); ++i) {
     funcs_to_infer_[i]->set_raw_inferred_name(func_name);
   }
   funcs_to_infer_.Rewind(0);
 }
 
 
 }  // namespace internal
 }  // namespace v8