Fix cast failures that will become runtime errors in Dart2.
Fix cast failures that will become runtime errors in Dart2.

tl;dr, in Dart2, you can't to do this:
  var x = [];
  x as List<String>

... where-as in Dart1 (and current versions of DDC with relaxed checks), this was fine.

PiperOrigin-RevId: 188602928

angulardart/angular_components,angulardart/angular_components,angulardart/angular_components