anchor.diff:    var l18 = const {1, 2};
     Expect.isTrue(l18 is Set<int>);
   
  -  // Class overriding `==`.
  -  class C {
  -    final int id;
  -    final String name;
  -    C(this.id, this.name);
  -    int get hashCode => id;
  -    bool operator==(Object other) => other is C && id == other.id;
  -    String toString() => "C($id, $name)";
  -  }
  -
  -  var v19 = {C(1, "a"), C(2, "a"), C("1", "b")};
  -  Expect.isTrue(l19 is LinkedHashSet<C>);
  +  var v19 = {C(1, "a"), C(2, "a"), C(1, "b")};
  +  Expect.isTrue(v19 is LinkedHashSet<C>);
     Expect.equals({C(1, "a"), C(2, "a")}, v19);
   
     var v23 = {1, 2.5};
  
positive.code:   var v24 = {1, false};
    Expect.isTrue(v24 is LinkedHashSet<Object>);
    const v26  = {1, false};
    Expect.isTrue(v26 is const Set<Object>);
  }
  
negative.code: // SharedOptions=--enable-experiment=set-literals
  import "../../Utils/expect.dart";
  import "dart:collection";
  
  // Class overriding `==`.
  class C {
    final int id;
    final String name;
    C(this.id, this.name);
    int get hashCode => id;
    bool operator==(Object other) => other is C && id == other.id;
    String toString() => "C($id, $name)";
  }
  
  main() {
    Expect.isTrue({} is LinkedHashMap<dynamic, dynamic>);
  