Enable messages in asserts by default

pkg/analyzer/test/generated/engine_test.dart

Index: pkg/analyzer/test/generated/engine_test.dart
diff --git a/pkg/analyzer/test/generated/engine_test.dart b/pkg/analyzer/test/generated/engine_test.dart
index 93b31083a1211a0dafaf6ca5e76bf6ac271d710a..5822a2d62232cd58141ded34094b023bc3e6796d 100644
--- a/pkg/analyzer/test/generated/engine_test.dart
+++ b/pkg/analyzer/test/generated/engine_test.dart
@@ -42,7 +42,6 @@ class AnalysisOptionsImplTest {
     modifiedOptions.dart2jsHint = true;
     modifiedOptions.disableCacheFlushing = true;
     modifiedOptions.enableAssertInitializer = true;
-    modifiedOptions.enableAssertMessage = true;
     modifiedOptions.enableLazyAssignmentOperators = true;
     modifiedOptions.enableStrictCallChecks = true;
     modifiedOptions.enableSuperMixins = true;
@@ -71,8 +70,6 @@ class AnalysisOptionsImplTest {
         defaultOptions.disableCacheFlushing);
     expect(modifiedOptions.enableAssertInitializer,
         defaultOptions.enableAssertInitializer);
-    expect(modifiedOptions.enableAssertMessage,
-        defaultOptions.enableAssertMessage);
     expect(modifiedOptions.enableLazyAssignmentOperators,
         defaultOptions.enableLazyAssignmentOperators);
     expect(modifiedOptions.enableStrictCallChecks,