Unexpected FutureOr<dynamic>% in CFE output

[chloestefantsova]

The CFE produces a FutureOr type with unexpected Nullability.undetermined.

The following program demonstrates the issue:

foo(dynamic y) async {
  var a = await (<X>(List<X> Function() x, X x2) => x2)(() => y, throw 0);
}

The compiled program contains the unexpected FutureOr<dynamic>%.

library /*isNonNullableByDefault*/;
import self as self;
import "dart:core" as core;

static method foo(dynamic y) → dynamic async /* futureValueType= dynamic */ {
  dynamic a = await(<X extends core::Object? = dynamic>(() → core::List<X%> x, X% x2) → X% => x2)<FutureOr<dynamic>%>(() → core::List<FutureOr<dynamic>%> => y as{TypeError,ForDynamic,ForNonNullableByDefault} core::List<FutureOr<dynamic>%>, throw 0){(() → core::List<FutureOr<dynamic>?>, FutureOr<dynamic>?) → FutureOr<dynamic>?};
}

[chloestefantsova]

I'm working on a fix at https://dart-review.googlesource.com/c/sdk/+/240722.