Async is no longer optional

pkg/analyzer/test/src/task/options_test.dart

Index: pkg/analyzer/test/src/task/options_test.dart
diff --git a/pkg/analyzer/test/src/task/options_test.dart b/pkg/analyzer/test/src/task/options_test.dart
index def44fd54721d224d17c9e8b4ff6c6169dea0fcb..8e50dc03f273c6faa7348de98030b4e12d0a6d4b 100644
--- a/pkg/analyzer/test/src/task/options_test.dart
+++ b/pkg/analyzer/test/src/task/options_test.dart
@@ -54,23 +54,6 @@ analyzer:
     expect(analysisOptions.strongMode, false);
   }
 
-  test_configure_enableAsync() {
-    configureContext('''
-analyzer:
-  language:
-''');
-    expect(analysisOptions.enableAsync, true);
-  }
-
-  test_configure_enableAsync_false() {
-    configureContext('''
-analyzer:
-  language:
-    enableAsync: false
-''');
-    expect(analysisOptions.enableAsync, false);
-  }
-
   test_configure_enableGenericMethods() {
     expect(analysisOptions.enableGenericMethods, false);
     configureContext('''