Server options file gets a dot.

pkg/analysis_server/lib/src/server_options.dart

Index: pkg/analysis_server/lib/src/server_options.dart
diff --git a/pkg/analysis_server/lib/src/server_options.dart b/pkg/analysis_server/lib/src/server_options.dart
index 4a59efb196f41cfa65b2b939d705d16fe1deb043..ab1e0120586d3a085e603a003d9fefe1e1443ad2 100644
--- a/pkg/analysis_server/lib/src/server_options.dart
+++ b/pkg/analysis_server/lib/src/server_options.dart
@@ -10,7 +10,8 @@ import 'dart:io';
 import 'package:path/path.dart' as path;
 import 'package:yaml/yaml.dart';
 
-const _optionsFileName = 'dart_analysis_server.options';
+//TODO: consider renaming (https://github.com/dart-lang/sdk/issues/23927)
+const _optionsFileName = '.dart_analysis_server.yaml';
 
 /// The shared options instance.
 ServerOptions _serverOptions;