Add refresh button to stack trace page.

runtime/bin/vmservice/client/lib/src/observatory_elements/stack_trace.dart

Index: runtime/bin/vmservice/client/lib/src/observatory_elements/stack_trace.dart
diff --git a/runtime/bin/vmservice/client/lib/src/observatory_elements/stack_trace.dart b/runtime/bin/vmservice/client/lib/src/observatory_elements/stack_trace.dart
index 49928313d355a89b3f137d9a19a8e36b84de3bb2..e128007a5a89b0022058168800e8ca1b2c60a570 100644
--- a/runtime/bin/vmservice/client/lib/src/observatory_elements/stack_trace.dart
+++ b/runtime/bin/vmservice/client/lib/src/observatory_elements/stack_trace.dart
@@ -4,6 +4,7 @@
 
 library stack_trace_element;
 
+import 'dart:html';
 import 'observatory_element.dart';
 import 'package:polymer/polymer.dart';
 
@@ -12,4 +13,13 @@ class StackTraceElement extends ObservatoryElement {
   @published Map trace = toObservable({});
 
   StackTraceElement.created() : super.created();
-}
+
+  void refresh(Event e, var detail, Node target) {
+    var url = app.locationManager.currentIsolateRelativeLink('stacktrace');
+    app.requestManager.requestMap(url).then((map) {
+        trace = map;
+    }).catchError((e, trace) {
+        Logger.root.severe('Error while reloading stack trace: $e\n$trace');
+    });
+  }
+}