Show tooltip with local variable value in Observatory debugger

runtime/observatory/lib/utils.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.
 
 library utils;
 
+import 'dart:async';
 import 'dart:math';
 
 class Utils {
 
   static String formatPercentNormalized(double x) {
     var percent = 100.0 * x;
     return '${percent.toStringAsFixed(2)}%';
   }
 
   static String formatPercent(num a, num total) {
@@ skipping 116 matching lines @@
     }
     return '${seconds}s';
   }
 
   static String formatSeconds(double x) {
     return x.toStringAsFixed(2);
   }
 
   static bool runningInJavaScript() => identical(1.0, 1);
 }
+
+/// A [Task] that can be scheduled on the Dart event queue.
+class Task {
+  Timer _timer;
+  final Function callback;
+
+  Task(this.callback);
+
+  /// Queue [this] to run on the next Dart event queue pump. Does nothing
+  /// if [this] is already queued.
+  queue() {
+    if (_timer != null) {
+      // Already scheduled.
+      return;
+    }
+    _timer = new Timer(Duration.ZERO, () {
+     _timer = null;
+     callback();
+    });
+  }
+}