avoid spread args

tool/input_sdk/private/ddc_runtime/generators.dart

Index: tool/input_sdk/private/ddc_runtime/generators.dart
diff --git a/tool/input_sdk/private/ddc_runtime/generators.dart b/tool/input_sdk/private/ddc_runtime/generators.dart
index 4c1f17aecbe6ccf8e4276e2208156d61ccedcbd5..b8138d7b4dda863c3c20bcaa2fc90a6c9ba80675 100644
--- a/tool/input_sdk/private/ddc_runtime/generators.dart
+++ b/tool/input_sdk/private/ddc_runtime/generators.dart
@@ -47,8 +47,8 @@ async_(gen, T, @rest args) => JS('', '''(() => {
     // Chain the Future so `await` receives the Future's value.
     return future.then($dynamic)(onValue, {onError: onError});
   }
-  return ${getGenericClass(Future)}(T).new(function() {
-    iter = $gen(...$args)[Symbol.iterator]();
+  return ${getGenericClass(Future)}($T).new(function() {
+    iter = $gen.apply(null, $args)[Symbol.iterator]();
     return onValue();
   });
 })()''');