Upgrade some tests to use annotations instead of 'clever' confuse() function

tests/language/super_bound_closure_test.dart

Index: tests/language/super_bound_closure_test.dart
diff --git a/tests/language/super_bound_closure_test.dart b/tests/language/super_bound_closure_test.dart
index 1663c936a5ca9899d6d7a8f46bca7842686e67a9..992d4926e1d149cde63abf153894f4c2f3b05960 100644
--- a/tests/language/super_bound_closure_test.dart
+++ b/tests/language/super_bound_closure_test.dart
@@ -4,6 +4,10 @@
 
 import "package:expect/expect.dart";
 
+@AssumeDynamic()
+@NoInline()
+confuse(x) => x;
+
 class A {
   bar([var optional = 1]) => 498 + optional;
   bar2({ namedOptional: 2 }) => 40 + namedOptional;
@@ -93,11 +97,6 @@ class B extends A {
   lastWhere(x, { orElse: 555 }) => -1;
 }
 
-confuse(x) {
-  if (new DateTime.now().millisecondsSinceEpoch == 42) return confuse(x - 1);
-  return x;
-}
-
 main() {
   var list = [new A(), new B(), [], "foo" ];
   var a = list[confuse(0)];