Tweak unittest compact config a bit and don't use it on bots.

pkg/barback/test/utils.dart

Index: pkg/barback/test/utils.dart
diff --git a/pkg/barback/test/utils.dart b/pkg/barback/test/utils.dart
index 1ec2c3df24a768df130bd47264a69eb941d0f843..6468d871e0b3fe4eb5e112c9441f811bb436f8c0 100644
--- a/pkg/barback/test/utils.dart
+++ b/pkg/barback/test/utils.dart
@@ -12,9 +12,7 @@ import 'package:barback/barback.dart';
 import 'package:barback/src/asset_graph.dart';
 import 'package:pathos/path.dart' as pathos;
 import 'package:scheduled_test/scheduled_test.dart';
-
-// TODO(rnystrom): Get rid of this or find a better path for it.
-import '../../../sdk/lib/_internal/pub/test/command_line_config.dart';
+import 'package:unittest/compact_vm_config.dart';
 
 var _configured = false;
 
@@ -29,7 +27,7 @@ int _nextBuildResult;
 void initConfig() {
   if (_configured) return;
   _configured = true;
-  unittestConfiguration = new CommandLineConfiguration();
+  useCompactVMConfiguration();
 }
 
 /// Creates a new [AssetProvider] and [AssetGraph] with the given [assets] and