[ast] Mark temporaries as maybe-assigned by default.

src/parsing/parser.cc

 // 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.
 
 #include "src/parsing/parser.h"
 
 #include <memory>
 
 #include "src/api.h"
 #include "src/ast/ast-expression-rewriter.h"
@@ skipping 2973 matching lines @@
   // }
   Block* result = factory()->NewBlock(nullptr, 2, true, kNoSourcePosition);
 
   // .promise = %AsyncFunctionPromiseCreate();
   Statement* set_promise;
   {
     Expression* create_promise = factory()->NewCallRuntime(
         Context::ASYNC_FUNCTION_PROMISE_CREATE_INDEX,
         new (zone()) ZoneList<Expression*>(0, zone()), kNoSourcePosition);
     Assignment* assign_promise = factory()->NewAssignment(
-        Token::INIT, factory()->NewVariableProxy(PromiseVariable()),
+        Token::ASSIGN, factory()->NewVariableProxy(PromiseVariable()),
         create_promise, kNoSourcePosition);
     set_promise =
         factory()->NewExpressionStatement(assign_promise, kNoSourcePosition);
   }
   result->statements()->Add(set_promise, zone());
 
   // catch (.catch) { return %RejectPromise(.promise, .catch), .promise }
   Scope* catch_scope = NewScope(CATCH_SCOPE);
   catch_scope->set_is_hidden();
   Variable* catch_variable =
@@ skipping 2013 matching lines @@
 
   return final_loop;
 }
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8