48b1656690
According to our typing rules a Set<Apple> is a Set<Fruit>. However, before this change, we couldn't use it as a Set<Fruit>:
===
bool foo(Set<Fruit> fruits) {
// Would yield a type-error since we actually got a Set<Apple>.
return fruits.contains(new Banana());
}
foo(new Set<Apple>());
===
R=ajohnsen@google.com, blois@google.com, lrn@google.com
Review URL: https://codereview.chromium.org//14246008
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@24326 260f80e4-7a28-3924-810f-c04153c831b5