Wait for a timed-out test's tear-down logic.

lib/src/frontend/timeout.dart

Index: lib/src/frontend/timeout.dart
diff --git a/lib/src/frontend/timeout.dart b/lib/src/frontend/timeout.dart
index 78fea385fe775b667fdd6fb1a3571c51fa5c76d4..2e4f165e0db2898edaafe60d363b4a7edb7246a7 100644
--- a/lib/src/frontend/timeout.dart
+++ b/lib/src/frontend/timeout.dart
@@ -59,4 +59,10 @@ class Timeout {
     if (this == none) return null;
     return duration == null ? base * scaleFactor : duration;
   }
+
+  String toString() {
+    if (duration != null) return duration.toString();
+    if (scaleFactor != null) return "${scaleFactor}x";
+    return "none";
+  }
 }