Replace try/finally with PerformanceTag.makeCurrentWhile().

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

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // 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 code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.utilities.general;
 
 import 'dart:profiler';
@@ skipping 62 matching lines @@
    * Return the label for this [PerformanceTag].
    */
   String get label;
 
   /**
    * Make this the current tag for the isolate, and return the previous tag.
    */
   PerformanceTag makeCurrent();
 
   /**
+   * Make this the current tag for the isolate, run [f], and restore the
+   * previous tag. Returns the result of invoking [f].
+   */
+  makeCurrentWhile(f());
+
+  /**
    * Reset the total time tracked by all [PerformanceTag]s to zero.
    */
   static void reset() {
     for (_PerformanceTagImpl tag in _PerformanceTagImpl.all) {
       tag.stopwatch.reset();
     }
   }
 }
 
 class _PerformanceTagImpl implements PerformanceTag {
@@ skipping 14 matching lines @@
    */
   final UserTag userTag;
 
   /**
    * Stopwatch tracking the amount of time this [PerformanceTag] has been the
    * current tag for the isolate.
    */
   final Stopwatch stopwatch;
 
   _PerformanceTagImpl(String label)
-      : userTag = new UserTag(label), stopwatch = new Stopwatch() {
+      : userTag = new UserTag(label),
+        stopwatch = new Stopwatch() {
     all.add(this);
   }
 
   @override
   int get elapsedMs => stopwatch.elapsedMilliseconds;
 
   @override
   String get label => userTag.label;
 
   @override
   PerformanceTag makeCurrent() {
     if (identical(this, current)) {
       return current;
     }
     _PerformanceTagImpl previous = current;
     previous.stopwatch.stop();
     stopwatch.start();
     current = this;
     userTag.makeCurrent();
     return previous;
   }
+
+  makeCurrentWhile(f()) {
+    PerformanceTag prevTag = makeCurrent();
+    try {
+      return f();
+    } finally {
+      prevTag.makeCurrent();
+    }
+  }
 }