UI for setting/clearing closure-specific breakpoints.

runtime/observatory/lib/src/elements/instance_view.dart

Index: runtime/observatory/lib/src/elements/instance_view.dart
diff --git a/runtime/observatory/lib/src/elements/instance_view.dart b/runtime/observatory/lib/src/elements/instance_view.dart
index 1513558ba699fe4925179f0d92fad5fa651da080..96a3b746ceb3b74bf89921d54cb15e1ca44b4800 100644
--- a/runtime/observatory/lib/src/elements/instance_view.dart
+++ b/runtime/observatory/lib/src/elements/instance_view.dart
@@ -19,6 +19,16 @@ class InstanceViewElement extends ObservatoryElement {
     return instance.evaluate(expression);
   }
 
+  Future setBreakOnActivation() {
+    return instance.isolate.addBreakOnActivation(instance)
+        .then((_) => refresh());
+  }
+
+  Future clearBreakOnActivation() {
+    return instance.isolate.removeBreakpoint(instance.activationBreakpoint)
+        .then((_) => refresh());
+  }
+
   Future refresh() {
     return instance.reload();
   }