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

tests/language/super_bound_closure_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
 
+@AssumeDynamic()
+@NoInline()
+confuse(x) => x;
+
 class A {
   bar([var optional = 1]) => 498 + optional;
   bar2({ namedOptional: 2 }) => 40 + namedOptional;
   bar3(x, [var optional = 3]) => x + 498 + optional;
   bar4(x, { namedOptional: 4 }) => 422 + x + namedOptional;
 
   // Gee is the same as bar, but we make sure that gee is used. Potentially
   // this yields different code if the redirecting stub exists.
   gee([var optional = 1]) => 498 + optional;
   gee2({ namedOptional: 2 }) => 40 + namedOptional;
@@ skipping 69 matching lines @@
   trim({ namedOptional: 22 }) => -1;
   sublist(x, [optional = 44]) => -1;
   splitMapJoin(x, { onMatch: 55, onNonMatch: 66}) => -1;
 
   shuffle([var optional = 121]) => -1;
   toList({ growable: 2233 }) => -1;
   lastIndexOf(x, [optional = 424]) => -1;
   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)];
   var b = list[confuse(1)];
   var ignored = list[confuse(2)];
   var ignored2 = list[confuse(3)];
 
   var t = b.gee() + b.gee2() + b.gee3(9) + b.gee4(19);
   Expect.equals(-4, t); /// 01: continued
   t = b.shuffle() + b.toList() + b.lastIndexOf(1) + b.lastWhere(2);
@@ skipping 28 matching lines @@
 
   Expect.equals(12463, b.fooIntercept21());
   Expect.equals(12344, b.fooIntercept22());
   Expect.equals(15364, b.fooIntercept23());
   Expect.equals(13208, b.fooIntercept24());
   Expect.equals(14742, b.fooIntercept25());
   Expect.equals(14291, b.fooIntercept26());
   Expect.equals(1768, b.fooIntercept27());
   Expect.equals(1771, b.fooIntercept28());
 }