Allow Observatory to run as a hosted web service

runtime/bin/vmservice/client/lib/src/elements/nav_bar.html

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="observatory_element.html">
 
 <polymer-element name="nav-bar" extends="observatory-element">
   <template>
     <link rel="stylesheet" href="css/shared.css">
     <style>
       nav {
         position: fixed;
         width: 100%;
@@ skipping 173 matching lines @@
       <button class="black" on-click="{{ back }}">&#9664;</button>
       <button class="black" on-click="{{ forward }}">&#9654;</button>
     </li>
     -->
   </template>
 </polymer-element>
 
 <polymer-element name="top-nav-menu">
   <template>
     <nav-menu link="/vm" anchor="Observatory" last="{{ last }}">
+      <nav-menu-item link="/vm-connect/" anchor="Connect to a different VM"></nav-menu-item>
       <content></content>
     </nav-menu>
   </template>
 </polymer-element>
 
 <polymer-element name="isolate-nav-menu" extends="observatory-element">
   <template>
     <nav-menu link="{{ hashLinkWorkaround }}" anchor="{{ isolate.name }}" last="{{ last }}">
       <nav-menu-item link="{{ isolate.relativeLink('stacktrace') }}"
                      anchor="stack trace"></nav-menu-item>
@@ skipping 22 matching lines @@
 <polymer-element name="class-nav-menu" extends="observatory-element">
   <template>
     <nav-menu link="{{ cls.link }}"
               anchor="{{ cls.name }}" last="{{ last }}">
       <content></content>
     </nav-menu>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="nav_bar.dart"></script>