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

tests/language/generic_instanceof4_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.
 // Test that instanceof works correctly with type variables.
 
 import "package:expect/expect.dart";
 
 class A<T> {
+  @NoInline()
   foo(x) {
-    // Don't inline.
-    if (new DateTime.now().millisecondsSinceEpoch == 42) return foo(x);
     return x is T;
   }
 }
 
 class BB {}
 
 class B<T> implements BB {
+  @NoInline()
   foo() {
-    // Don't inline.
-    if (new DateTime.now().millisecondsSinceEpoch == 42) return foo();
     return new A<T>().foo(new B());
   }
 }
 
 main() {
   Expect.isTrue(new B<BB>().foo());
 }