Add breadcrumb for the VM.

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

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="nav_bar.html">
 <link rel="import" href="observatory_element.html">
 <link rel="import" href="script_inset.html">
 <link rel="import" href="view_footer.html">
 
 <polymer-element name="script-view" extends="observatory-element">
 <template>
   <link rel="stylesheet" href="css/shared.css">
   <nav-bar>
     <top-nav-menu></top-nav-menu>
-    <isolate-nav-menu isolate="{{ script.isolate }}">
-    </isolate-nav-menu>
+    <vm-nav-menu vm="{{ script.isolate.vm }}"></vm-nav-menu>
+    <isolate-nav-menu isolate="{{ script.isolate }}"></isolate-nav-menu>
     <library-nav-menu library="{{ script.library }}"></library-nav-menu>
     <nav-menu link="{{ makeLink('/inspect', script) }}" anchor="{{ script.name }}" last="{{ true }}"></nav-menu>
     <nav-refresh callback="{{ refreshCoverage }}" label="Refresh Coverage"></nav-refresh>
     <nav-refresh callback="{{ refresh }}"></nav-refresh>
   </nav-bar>
 
   <template if="{{ app.locationManager.internalArguments['pos'] == null }}">
     <script-inset id="scriptInset" script="{{ script }}">
       <h1>script {{ script.name }}</h1>
     </script-inset>
   </template>
 
   <template if="{{ app.locationManager.internalArguments['pos'] != null }}">
     <script-inset id="scriptInset" script="{{ script }}"
                   currentPos="{{ app.locationManager.internalArguments['pos'] | parseInt }}">
       <h1>script {{ script.name }}</h1>
     </script-inset>
   </template>
 
   <view-footer></view-footer>
 </template>
 </polymer-element>
 
 <script type="application/dart" src="script_view.dart"></script>