Disable closure wrapping by default

test/dart_codegen/expect/async/timer.dart

 part of dart.async;
  abstract class Timer {factory Timer(Duration duration, void callback()) {
   if (Zone.current == Zone.ROOT) {
     return Zone.current.createTimer(duration, callback);
     }
    return Zone.current.createTimer(duration, Zone.current.bindCallback(callback, runGuarded: true));
   }
  factory Timer.periodic(Duration duration, void callback(Timer timer)) {
   if (Zone.current == Zone.ROOT) {
     return Zone.current.createPeriodicTimer(duration, callback);
     }
-   return Zone.current.createPeriodicTimer(duration, ((__x129) => DEVC$RT.wrap((dynamic f(dynamic __u124)) {
-    dynamic c(dynamic x0) => f(x0);
-     return f == null ? null : c;
-    }
-  , __x129, __t127, __t125, "Wrap", """line 80, column 19 of dart:async/timer.dart: """, __x129 is __t125))(Zone.current.bindUnaryCallback(callback, runGuarded: true)));
+   return Zone.current.createPeriodicTimer(duration, ((__x104) => DEVC$RT.cast(__x104, __t102, __t100, "CompositeCast", """line 80, column 19 of dart:async/timer.dart: """, __x104 is __t100, false))(Zone.current.bindUnaryCallback(callback, runGuarded: true)));
   }
  static void run(void callback()) {
   new Timer(Duration.ZERO, callback);
   }
  void cancel();
  bool get isActive;
  external static Timer _createTimer(Duration duration, void callback());
  external static Timer _createPeriodicTimer(Duration duration, void callback(Timer timer));
 }
- typedef void __t125(Timer __u126);
- typedef dynamic __t127(dynamic __u128);
+ typedef void __t100(Timer __u101);
+ typedef dynamic __t102(dynamic __u103);