[async-await] don't eagerly resolve Promise before finally blocks have executed

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index d42cb0c49a3b90dd84b6bb61b04ca88f523826b1..610bf5562dd026da87dc57ad69e4daabd8bbd745 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -1611,8 +1611,6 @@ Expression* Parser::RewriteReturn(Expression* return_value, int pos) {
   }
   if (is_generator()) {
     return_value = BuildIteratorResult(return_value, true);
-  } else if (is_async_function()) {
-    return_value = BuildResolvePromise(return_value, return_value->position());
   }
   return return_value;
 }
@@ -3647,6 +3645,9 @@ void Parser::PrepareAsyncFunctionBody(ZoneList<Statement*>* body,
   if (function_state_->generator_object_variable() == nullptr) {
     PrepareGeneratorVariables();
   }
+  Variable* promise_var = PromiseVariable();
+  DCHECK_NOT_NULL(promise_var);
+  USE(promise_var);
 }
 
 // This method completes the desugaring of the body of async_function.
@@ -3660,7 +3661,6 @@ void Parser::RewriteAsyncFunctionBody(ZoneList<Statement*>* body,
   //   })
   // }
 
-  return_value = BuildResolvePromise(return_value, return_value->position());
   body->Add(
       factory()->NewReturnStatement(return_value, return_value->position()),
       zone());