Case-insensitive string contains

main.dart

void main() {
  var s = "Let's dance the macarena";

  {
	  var word = "Dance";
    bool ok = s.toUpperCase().contains(word.toUpperCase());
    print(ok);
  }
  {
	  var word = "dance";
    bool ok = s.toUpperCase().contains(word.toUpperCase());
    print(ok);
  }
  {
	  var word = "Duck";
    bool ok = s.toUpperCase().contains(word.toUpperCase());
    print(ok);
  }
}