Show tooltip with local variable value in Observatory debugger

runtime/observatory/lib/utils.dart

Index: runtime/observatory/lib/utils.dart
diff --git a/runtime/observatory/lib/utils.dart b/runtime/observatory/lib/utils.dart
index 522a11edda9893b00eda8977395cf00c9803f92e..c696529c750b20bfcc1e09bf1d15131c2ab5018b 100644
--- a/runtime/observatory/lib/utils.dart
+++ b/runtime/observatory/lib/utils.dart
@@ -4,6 +4,7 @@
 
 library utils;
 
+import 'dart:async';
 import 'dart:math';
 
 class Utils {
@@ -140,3 +141,24 @@ class Utils {
 
   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();
+    });
+  }
+}