[analyzer] Deprecate package:analyzer/src/generated/timestamped_data.dart.

Now that dartdoc has been upgraded to
dart-lang/dartdoc@d683b47
("Stop importing TimestampedData from package:analyzer/src"), it is
safe to deprecate this file.

This file will be removed in analyzer 9.0.0.

Change-Id: I6a6a6964704e4dd2a79876d0995dae70aa022ae8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/447241
Commit-Queue: Konstantin Shcheglov <[email protected]>
Auto-Submit: Paul Berry <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>

Author: stereotype441

pkg/analyzer/lib/src/generated/engine.dart

@@ -13,9 +13,8 @@ import 'package:meta/meta.dart';
 
 export 'package:analyzer/dart/analysis/analysis_options.dart';
 export 'package:analyzer/error/listener.dart' show RecordingDiagnosticListener;
+export 'package:analyzer/source/timestamped_data.dart' show TimestampedData;
 export 'package:analyzer/src/dart/analysis/analysis_options.dart';
-export 'package:analyzer/src/generated/timestamped_data.dart'
-    show TimestampedData;
 
 /// A context in which a single analysis can be performed and incrementally
 /// maintained. The context includes such information as the version of the SDK

pkg/analyzer/lib/src/generated/timestamped_data.dart

@@ -2,10 +2,15 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// This export is needed because package `dartdoc` imports the `TimestampedData`
-// class from here.
+@Deprecated('Please use package:analyzer/source/timestamped_data.dart instead.')
+library;
+
+// This export is needed because there are versions of package `dartdoc` that
+// import the `TimestampedData` class from here.
+//
+// All of those versions have an analyzer constraint < 9.0.0, so once the
+// analyzer version gets bumped to 9.0.0, it will be safe to remove this file.
 //
-// TODO(paulberry): update dartdoc's import, so that this library can be
-// deprecated and eventually removed.
+// TODO(paulberry): remove this file in analyzer version 9.0.0.
 
 export 'package:analyzer/source/timestamped_data.dart' show TimestampedData;