vm/observatory: Clean up script access

runtime/bin/vmservice/client/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">
 
 <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>
+    <nav-menu link="{{ script.owningLibrary.link }}" anchor="{{ script.owningLibrary.name }}"></nav-menu>
     <nav-menu link="{{ script.link }}" anchor="{{ script.name }}" last="{{ true }}"></nav-menu>
     <nav-refresh callback="{{ refreshCoverage }}" label="Refresh Coverage"></nav-refresh>
     <nav-refresh callback="{{ refresh }}"></nav-refresh>
     <nav-control></nav-control>
   </nav-bar>
 
   <template if="{{ args['pos'] == null }}">
     <script-inset id="scriptInset" script="{{ script }}">
       <h1>script {{ script.name }}</h1>
     </script-inset>
   </template>
 
   <template if="{{ args['pos'] != null }}">
     <script-inset id="scriptInset" script="{{ script }}"
                   currentPos="{{ args['pos'] | parseInt }}">
       <h1>script {{ script.name }}</h1>
     </script-inset>
   </template>
 
 </template>
 </polymer-element>
 
 <script type="application/dart" src="script_view.dart"></script>