[dart2js] Exporting as package: to allow non-SDK usage

Change-Id: I0235f524904a1a4c54c83161eb51ab0277473d1e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/244180
Reviewed-by: Joshua Litt <joshualitt@google.com>
Commit-Queue: Mark Zhou <markzipan@google.com>
diff --git a/pkg/dart2js_runtime_metrics/lib/_runtime_metrics_dart2js.dart b/pkg/dart2js_runtime_metrics/lib/_runtime_metrics_dart2js.dart
index 3aa7cbb..ab66483 100644
--- a/pkg/dart2js_runtime_metrics/lib/_runtime_metrics_dart2js.dart
+++ b/pkg/dart2js_runtime_metrics/lib/_runtime_metrics_dart2js.dart
@@ -2,4 +2,5 @@
 // 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.
 
-export 'dart:_dart2js_runtime_metrics' show runtimeMetrics;
+export 'package:dart2js_runtime_metrics/runtime_metrics.dart'
+    show runtimeMetrics;
diff --git a/pkg/dart2js_runtime_metrics/lib/_startup_metrics_dart2js.dart b/pkg/dart2js_runtime_metrics/lib/_startup_metrics_dart2js.dart
index 021c666..424ec11 100644
--- a/pkg/dart2js_runtime_metrics/lib/_startup_metrics_dart2js.dart
+++ b/pkg/dart2js_runtime_metrics/lib/_startup_metrics_dart2js.dart
@@ -2,4 +2,5 @@
 // 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.
 
-export 'dart:_dart2js_runtime_metrics' show startupMetrics;
+export 'package:dart2js_runtime_metrics/startup_metrics.dart'
+    show startupMetrics;