Copy perf.dart into front_end/tool.

pkg/front_end/tool/perf.dart

Index: pkg/front_end/tool/perf.dart
diff --git a/pkg/analyzer_cli/tool/perf.dart b/pkg/front_end/tool/perf.dart
similarity index 98%
copy from pkg/analyzer_cli/tool/perf.dart
copy to pkg/front_end/tool/perf.dart
index 40a747ab1e27e473bb416b1f1b48c6ff7dc63293..d56012e6529e8f68b4f3e72664c5adac4280b900 100644
--- a/pkg/analyzer_cli/tool/perf.dart
+++ b/pkg/front_end/tool/perf.dart
@@ -2,8 +2,8 @@
 // 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.
 
-/// An entrypoint used to run portions of analyzer and measure its performance.
-library analyzer_cli.tool.perf;
+/// An entrypoint used to run portions of front_end and measure its performance.
+library front_end.tool.perf;
 
 import 'dart:async';
 import 'dart:io' show exit;