[flutter_tools] disable fast-start on routes test (#49473)
diff --git a/dev/devicelab/bin/tasks/routing_test.dart b/dev/devicelab/bin/tasks/routing_test.dart
index 6029ada..ac15daa 100644
--- a/dev/devicelab/bin/tasks/routing_test.dart
+++ b/dev/devicelab/bin/tasks/routing_test.dart
@@ -34,7 +34,8 @@
print('run: starting...');
final Process run = await startProcess(
path.join(flutterDirectory.path, 'bin', 'flutter'),
- <String>['run', '--verbose', '--disable-service-auth-codes', '-d', device.deviceId, '--route', '/smuggle-it', 'lib/route.dart'],
+ // --fast-start does not support routes.
+ <String>['run', '--verbose', '--disable-service-auth-codes', '--no-fast-start', '-d', device.deviceId, '--route', '/smuggle-it', 'lib/route.dart'],
);
run.stdout
.transform<String>(utf8.decoder)