Add breadcrumb for the VM.

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

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="curly_block.html">
 <link rel="import" href="eval_box.html">
 <link rel="import" href="function_ref.html">
 <link rel="import" href="isolate_summary.html">
 <link rel="import" href="library_ref.html">
 <link rel="import" href="nav_bar.html">
 <link rel="import" href="observatory_element.html">
 <link rel="import" href="script_ref.html">
 <link rel="import" href="view_footer.html">
 
 <polymer-element name="vm-view" extends="observatory-element">
   <template>
     <link rel="stylesheet" href="css/shared.css">
 
     <nav-bar>
-      <top-nav-menu last="{{ true }}"></top-nav-menu>
+      <top-nav-menu last="{{ false }}"></top-nav-menu>
+      <vm-nav-menu vm="{{ vm }}" last="{{ true }}"></vm-nav-menu>
       <nav-refresh callback="{{ refresh }}"></nav-refresh>
     </nav-bar>
 
     <div class="content">
       <h1>VM</h1>
       <div class="memberList">
         <div class="memberItem">
           <div class="memberName">version</div>
           <div class="memberValue">{{ vm.version }}</div>
         </div>
@@ skipping 37 matching lines @@
           <isolate-summary isolate="{{ isolate }}"></isolate-summary>
         </li>
         <hr>
       </template>
     </ul>
     <view-footer></view-footer>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="vm_view.dart"></script>