Add breadcrumb for the VM.

runtime/observatory/lib/src/elements/object_view.html

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="class_ref.html">
 <link rel="import" href="error_view.html">
 <link rel="import" href="field_ref.html">
 <link rel="import" href="function_ref.html">
 <link rel="import" href="inbound_reference.html">
 <link rel="import" href="instance_ref.html">
 <link rel="import" href="observatory_element.html">
 <link rel="import" href="object_common.html">
 <link rel="import" href="nav_bar.html">
 <link rel="import" href="eval_link.html">
 
 <polymer-element name="object-view" extends="observatory-element">
   <template>
     <link rel="stylesheet" href="css/shared.css">
     <nav-bar>
       <top-nav-menu></top-nav-menu>
+      <vm-nav-menu vm="{{ object.isolate.vm }}"></vm-nav-menu>
       <isolate-nav-menu isolate="{{ object.isolate }}"></isolate-nav-menu>
       <nav-menu link="." anchor="object" last="{{ true }}"></nav-menu>
       <nav-refresh callback="{{ refresh }}"></nav-refresh>
     </nav-bar>
 
     <div class="content">
       <object-common object="{{ object }}"></object-common>
     </div>
 
     <hr>
     <view-footer></view-footer>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="object_view.dart"></script>