Use generic functions in zones.

tests/lib_strong/async/stream_listen_zone_test.dart

 // Copyright (c) 2013, 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.
 
 library stream_listen_zeno_test;
 
 import "dart:async";
 import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 
@@ skipping 46 matching lines @@
       nextStep();
     }, onDone: () {
       Expect.identical(zone, Zone.current, name);
       if (overrideDone) throw "RUNNING WRONG ONDONE";
       callbackBits |= 4;
       nextStep();
     });
     registerExpect += 3;
     Expect.equals(registerExpect, registerCount, name);
   },
-      zoneSpecification:
-          new ZoneSpecification(registerCallback: (self, p, z, callback()) {
+      zoneSpecification: new ZoneSpecification(
+          registerCallback: <R>(self, p, z, R callback()) {
         Expect.identical(zone, self, name);
         registerCount++;
         return () {
           Expect.identical(zone, Zone.current, name);
-          callback();
+          return callback();
         };
-      }, registerUnaryCallback: (self, p, z, callback(a)) {
+      }, registerUnaryCallback: <R, T>(self, p, z, R callback(T a)) {
         Expect.identical(zone, self, name);
         registerCount++;
         return (a) {
           Expect.identical(zone, Zone.current, name);
-          callback(a);
+          return callback(a);
         };
-      }, registerBinaryCallback: (self, package, z, callback(a, b)) {
+      }, registerBinaryCallback:
+              <R, T1, T2>(self, package, z, R callback(T1 a, T2 b)) {
         Expect.identical(zone, self, name);
         registerCount++;
         return (a, b) {
           Expect.identical(zone, Zone.current, name);
-          callback(a, b);
+          return callback(a, b);
         };
       }));
 
   int expectedBits = 0;
   step = () {
     var stepName = "$name-$stepCount";
     Expect.identical(Zone.ROOT, Zone.current, stepName);
     Expect.equals(expectedBits, callbackBits, stepName);
     switch (stepCount++) {
       case 0:
@@ skipping 43 matching lines @@
         }
         Expect.equals(registerExpect, registerCount, stepName);
         controller.close();
         break;
       case 5:
         asyncEnd();
     }
   };
   step();
 }