Revert "Make Zone API strong mode clean."

tests/lib/async/zone_bind_callback_test.dart

Index: tests/lib/async/zone_bind_callback_test.dart
diff --git a/tests/lib/async/zone_bind_callback_test.dart b/tests/lib/async/zone_bind_callback_test.dart
index bb73bb75b48f526cd9a1cbedd3687c3b706da384..af6b24fc3178bf79ff74d87eb58643c5d31f31b7 100644
--- a/tests/lib/async/zone_bind_callback_test.dart
+++ b/tests/lib/async/zone_bind_callback_test.dart
@@ -14,8 +14,7 @@ main() {
 
   Expect.identical(Zone.ROOT, Zone.current);
   Zone forked = Zone.current.fork(specification: new ZoneSpecification(
-      registerCallback:
-          <R>(Zone self, ZoneDelegate parent, Zone origin, R f()) {
+      registerCallback: (Zone self, ZoneDelegate parent, Zone origin, f()) {
     // The zone is still the same as when origin.run was invoked, which
     // is the root zone. (The origin zone hasn't been set yet).
     Expect.identical(Zone.current, Zone.ROOT);
@@ -32,7 +31,7 @@ main() {
     Expect.identical(forked, Zone.current);
     return 99;
   };
-  var registered = forked.bindCallback(fun);
+  var registered = forked.bindCallback(fun, runGuarded: false);
   Expect.isFalse(identical(fun, registered));
 
   var result = registered();