Teach the Observatory about Contexts. Factor out object graph information from the instance view.

runtime/bin/vmservice/observatory/lib/src/elements/context_view.dart

Index: runtime/bin/vmservice/observatory/lib/src/elements/context_view.dart
diff --git a/runtime/bin/vmservice/observatory/lib/src/elements/stack_trace.dart b/runtime/bin/vmservice/observatory/lib/src/elements/context_view.dart
similarity index 54%
copy from runtime/bin/vmservice/observatory/lib/src/elements/stack_trace.dart
copy to runtime/bin/vmservice/observatory/lib/src/elements/context_view.dart
index f92630eb2b8b516123da7287fcaa834a4fc28b81..fdc05ec811a905c9900fa98b999d894c749b3c16 100644
--- a/runtime/bin/vmservice/observatory/lib/src/elements/stack_trace.dart
+++ b/runtime/bin/vmservice/observatory/lib/src/elements/context_view.dart
@@ -2,19 +2,20 @@
 // 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 stack_trace_element;
+library context_view_element;
 
-import 'package:polymer/polymer.dart';
+import 'dart:async';
 import 'observatory_element.dart';
 import 'package:observatory/service.dart';
+import 'package:polymer/polymer.dart';
 
-@CustomTag('stack-trace')
-class StackTraceElement extends ObservatoryElement {
-  @published ServiceMap trace;
+@CustomTag('context-view')
+class ContextViewElement extends ObservatoryElement {
+  @published Context context;
 
-  StackTraceElement.created() : super.created();
+  ContextViewElement.created() : super.created();
 
-  void refresh(var done) {
-    trace.reload().whenComplete(done);
+  void refresh(Function onDone) {
+    context.reload().whenComplete(onDone);
   }
 }