Add new <curly-block> element.

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

Index: runtime/bin/vmservice/client/lib/src/observatory_elements/curly_block.dart
diff --git a/runtime/bin/vmservice/client/lib/src/observatory_elements/curly_block.dart b/runtime/bin/vmservice/client/lib/src/observatory_elements/curly_block.dart
new file mode 100644
index 0000000000000000000000000000000000000000..8317efc6fe723421592c2193d49f616e43a49924
--- /dev/null
+++ b/runtime/bin/vmservice/client/lib/src/observatory_elements/curly_block.dart
@@ -0,0 +1,35 @@
+// Copyright (c) 2013, 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 curly_block_element;
+
+import 'package:logging/logging.dart';
+import 'package:polymer/polymer.dart';
+
+@CustomTag('curly-block')
+class CurlyBlockElement extends PolymerElement {
+  CurlyBlockElement.created() : super.created();
+
+  @observable bool expanded = false;
+  @observable bool busy = false;
+  @published var callback = null;
+
+  void doneCallback() {
+    print("done callback");
+    expanded = !expanded;
+    busy = false;
+  }
+
+  void toggleExpand(var a, var b, var c) {
+    if (busy) {
+      return;
+    }
+    if (callback != null) {
+      busy = true;
+      callback(!expanded, doneCallback);
+    } else {
+      expanded = !expanded;
+    }
+  }
+}