Use generic functions in zones.

sdk/lib/async/future.dart

Index: sdk/lib/async/future.dart
diff --git a/sdk/lib/async/future.dart b/sdk/lib/async/future.dart
index 67e2d76284d57fb4b504e3cba3beb8366f61678c..99de7171f6691cf0605a9e0ca0b594e387ba1d14 100644
--- a/sdk/lib/async/future.dart
+++ b/sdk/lib/async/future.dart
@@ -519,7 +519,7 @@ abstract class Future<T> {
     // context of all the previous iterations' callbacks.
     // This avoids, e.g., deeply nested stack traces from the stack trace
     // package.
-    nextIteration = Zone.current.bindUnaryCallback((bool keepGoing) {
+    nextIteration = Zone.current.bindUnaryCallbackGuarded((bool keepGoing) {
       while (keepGoing) {
         FutureOr<bool> result;
         try {
@@ -537,7 +537,7 @@ abstract class Future<T> {
         keepGoing = result;
       }
       doneSignal._complete(null);
-    }, runGuarded: true);
+    });
     nextIteration(true);
     return doneSignal;
   }