As I've already mentioned in other comments, I find that goals, use cases and background for Kotlin and Dart are pretty similar, so I would argue about "fairness" of the comparison.

Also, yes, Dart supports dynamic types, but for me it's not really advantage.

First, the current trend is actually moving towards static typing; and I fully agree with this trend, in medium- and large-sized projects static typing has a lot more benefits than dynamic one.

Second, without reflection support (and reflection is not supported by Flutter) we cannot use all the benefits and power that dynamic types can provide.