fix #28008, fix #28009 implement FutureOr<T>

tests/lib/async/future_or_bad_type_test.dart

Index: tests/lib/async/future_or_bad_type_test.dart
diff --git a/tests/lib/async/future_or_bad_type_test.dart b/tests/lib/async/future_or_bad_type_test.dart
index a74b30f6bd1b9d4831f343fabc98812113aeb37e..f0faf5373c246ae800d826f0d17df807c7d47fed 100644
--- a/tests/lib/async/future_or_bad_type_test.dart
+++ b/tests/lib/async/future_or_bad_type_test.dart
@@ -19,8 +19,9 @@ class A
 main() {
   // FutureOr<T> should be treated like `dynamic`. Dynamically the `T` is
   // completely ignored. It can be a malformed type.
-  Expect.isTrue(499 is FutureOr<A>);  /// 00: static type warning

[Jennifer Messerly, 2017/01/24 01:21:22]

I don't understand why this was expected to be a static warning. LMK if it makes
sense to you. I added another case that should be a warning.

[Leaf, 2017/01/24 21:56:27]

Can you ask Lasse what his intent was here?

[Jennifer Messerly, 2017/01/25 00:33:36]

Sure, +lrn@ for thoughts?

-  Expect.isTrue(499 is FutureOr<Does<Not<Exist>>>);  /// 01: static type warning
+  Expect.isTrue(499 is FutureOr<A>);
+  Expect.isTrue(499 is FutureOr<Does<Not<Exist>>>);  /// 00: static type warning
+  Expect.isTrue(499 is FutureOr<A, A>);              /// 01: static type warning
 
   var a = new A();
   Expect.isTrue(a.toString() is String);