Add Observatory support for UnlinkedCall, SingleTargetCache and SubtypeTestCache.

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

+// Copyright (c) 2017, 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.
+
+import 'dart:html';
+import 'dart:async';
+import 'package:observatory/models.dart' as M
+    show IsolateRef, SingleTargetCacheRef;
+import 'package:observatory/src/elements/helpers/rendering_scheduler.dart';
+import 'package:observatory/src/elements/helpers/tag.dart';
+import 'package:observatory/src/elements/helpers/uris.dart';
+
+class SingleTargetCacheRefElement extends HtmlElement implements Renderable {
+  static const tag =
+      const Tag<SingleTargetCacheRefElement>('singletargetcache-ref');
+
+  RenderingScheduler<SingleTargetCacheRefElement> _r;
+
+  Stream<RenderedEvent<SingleTargetCacheRefElement>> get onRendered =>
+      _r.onRendered;
+
+  M.IsolateRef _isolate;
+  M.SingleTargetCacheRef _singleTargetCache;
+
+  M.IsolateRef get isolate => _isolate;
+  M.SingleTargetCacheRef get singleTargetCache => _singleTargetCache;
+
+  factory SingleTargetCacheRefElement(
+      M.IsolateRef isolate, M.SingleTargetCacheRef singleTargetCache,
+      {RenderingQueue queue}) {
+    assert(isolate != null);
+    assert(singleTargetCache != null);
+    SingleTargetCacheRefElement e = document.createElement(tag.name);
+    e._r = new RenderingScheduler(e, queue: queue);
+    e._isolate = isolate;
+    e._singleTargetCache = singleTargetCache;
+    return e;
+  }
+
+  SingleTargetCacheRefElement.created() : super.created();
+
+  @override
+  void attached() {
+    super.attached();
+    _r.enable();
+  }
+
+  @override
+  void detached() {
+    super.detached();
+    _r.disable(notify: true);
+    children = [];
+  }
+
+  void render() {
+    children = [
+      new AnchorElement(
+          href: Uris.inspect(_isolate, object: _singleTargetCache))
+        ..children = [
+          new SpanElement()
+            ..classes = ['emphasize']
+            ..text = 'SingleTargetCache',
+          new SpanElement()..text = ' (${_singleTargetCache.target.name})'
+        ]
+    ];
+  }
+}