Revert two Kernel changes that were causing test failures.

tests/language_strong/async_return_types_test.dart

Index: tests/language_strong/async_return_types_test.dart
diff --git a/tests/language_2/async_return_types_test.dart b/tests/language_strong/async_return_types_test.dart
similarity index 59%
rename from tests/language_2/async_return_types_test.dart
rename to tests/language_strong/async_return_types_test.dart
index eae381b19112164da26fa11a218a0a362ba77ead..f763c090f5cd6cbf3d464f0347640d05900853f4 100644
--- a/tests/language_2/async_return_types_test.dart
+++ b/tests/language_strong/async_return_types_test.dart
@@ -14,17 +14,18 @@ Future<int> foo2() async {
   return 3;
 }
 
-Future<int> //# wrongTypeParameter: compile-time error
+Future<int> //# wrongTypeParameter: static type warning
 foo3() async {
   return "String";
 }
 
-Future<int, String> //# tooManyTypeParameters: compile-time error
+// Future<int, String> is treated like Future<dynamic>
+Future<int, String> //# tooManyTypeParameters: static type warning
 foo4() async {
   return "String";
 }
 
-int //# wrongReturnType: compile-time error
+int //# wrongReturnType: static type warning, dynamic type error
 foo5() async {
   return 3;
 }
@@ -34,27 +35,11 @@ Future<int> foo6() async {
   return new Future<int>.value(3);
 }
 
-Future<Future<int>> //# nestedFuture: compile-time error
+Future<Future<int>> //# nestedFuture: static type warning
 foo7() async {
   return new Future<int>.value(3);
 }
 
-Iterable<int> foo8() sync* {
-  yield 1;
-  // Can only have valueless return in sync* functions.
-  return
-      8 //# return_value_sync_star: compile-time error
-      ;
-}
-
-Stream<int> foo9() async* {
-  yield 1;
-  // Can only have valueless return in async* functions.
-  return
-      8 //# return_value_sync_star: compile-time error
-      ;
-}
-
 test() async {
   Expect.equals(3, await foo1());
   Expect.equals(3, await foo2());
@@ -63,8 +48,6 @@ test() async {
   Expect.equals(3, await foo5());
   Expect.equals(3, await await foo6());
   Expect.equals(3, await await foo7());
-  Expect.listEquals([1], foo8().toList());
-  Expect.listEquals([1], await foo9().toList());
 }
 
 main() {