chore(mock zone): sync() zone should also catch async exceptions

Author: jbdeboer

lib/mock/zone.dart

@@ -192,6 +192,8 @@ _createTimer(Function fn, Duration duration, bool periodic) {
  * will throw an exception.
  */
 sync(Function fn) => () {
+  _asyncErrors.clear();
+
   dart_async.runZoned(fn, zoneSpecification: new dart_async.ZoneSpecification(
     scheduleMicrotask: (_, __, ___, asyncFn) {
         throw ['scheduleMicrotask called from sync function.'];
@@ -202,8 +204,13 @@ sync(Function fn) => () {
     createPeriodicTimer:
         (_, __, ___, Duration period, void f(dart_async.Timer timer)) {
             throw ['periodic Timer created from sync function.'];
-        }
+        },
+    handleUncaughtError: (_, __, ___, e, s) => _asyncErrors.add([e, s])
     ));
+
+  _asyncErrors.forEach((e) {
+    throw "During runZoned: ${e[0]}.  Stack:\n${e[1]}";
+  });
 };
 
 class _TimerSpec implements dart_async.Timer {