Enable messages in asserts by default

pkg/analyzer/test/generated/static_type_warning_code_test.dart

Index: pkg/analyzer/test/generated/static_type_warning_code_test.dart
diff --git a/pkg/analyzer/test/generated/static_type_warning_code_test.dart b/pkg/analyzer/test/generated/static_type_warning_code_test.dart
index 82b972c5080a43786cf6a90bf31e1ce88e1edaa9..e4496f0c1168001e041b0b3072ee3edd48349f54 100644
--- a/pkg/analyzer/test/generated/static_type_warning_code_test.dart
+++ b/pkg/analyzer/test/generated/static_type_warning_code_test.dart
@@ -143,7 +143,6 @@ f() {}''');
     // assignment occurred outside an assert statement.  (Note that it is a
     // dubious practice for the computation of an assert message to have side
     // effects, since it is only evaluated if the assert fails).
-    resetWithOptions(new AnalysisOptionsImpl()..enableAssertMessage = true);
     assertErrorsInCode(
         '''
 class C {