The pub roller is blocked on

```
  error � The argument type 'JSArray<JSAny?>' can't be assigned to the parameter type 'JSArray<JSNumber>'.  � dev/benchmarks/macrobenchmarks/lib/web_benchmarks.dart:309:22 � argument_type_not_assignable
```

See https://github.com/flutter/flutter/pull/144852.

The fixes the typing so the next pub roll can (hopefully) succeed.