Fix Kernel tests

pkg/kernel/test/baseline_strong_mode_test.dart

Index: pkg/kernel/test/baseline_strong_mode_test.dart
diff --git a/pkg/kernel/test/baseline_strong_mode_test.dart b/pkg/kernel/test/baseline_strong_mode_test.dart
index 00ffcf0650d0489f65a9727e72cda524f6099d3b..e116f8578e11b3937eb99e23514056ce26ec1ed2 100644
--- a/pkg/kernel/test/baseline_strong_mode_test.dart
+++ b/pkg/kernel/test/baseline_strong_mode_test.dart
@@ -24,9 +24,14 @@ class StrongModeTest extends TestTarget {
   bool get strongMode => true;
 
   @override
-  List<String> transformProgram(Program program) {
-    List<String> errors = <String>[];
+  List<String> performModularTransformations(Program program) {
     new MixinFullResolution().transform(program);
+    return const <String>[];
+  }
+
+  @override
+  List<String> performGlobalTransformations(Program program) {
+    List<String> errors = <String>[];
     new InsertTypeChecks().transformProgram(program);
     new InsertCovarianceChecks().transformProgram(program);
     new TestTypeChecker(