Initial UI for Metrics in Observatory

runtime/bin/vmservice/observatory/lib/src/elements/vm_connect.html

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="nav_bar.html">
 <link rel="import" href="observatory_element.html">
 
 <polymer-element name="vm-connect-target" extends="observatory-element">
   <template>
     <style>
       .delete-button {
         padding: 4px;
         background: transparent;
         border: none !important;
       }
       .delete-button:hover {
         background: #ff0000;
       }
     </style>
     <link rel="stylesheet" href="css/shared.css">
     <span>
       <template if="{{ isCurrentTarget }}">
-        <a on-click="{{ connectToVm }}" href="{{ gotoLink('/vm') }}">{{ target.name }} (Connected)</a>
+        <a on-click="{{ connectToVm }}" _href="{{ gotoLink('/vm') }}">{{ target.name }} (Connected)</a>
       </template>
       <template if="{{ !isCurrentTarget }}">
-        <a on-click="{{ connectToVm }}" href="{{ gotoLink('/vm') }}">{{ target.name }}</a>
+        <a on-click="{{ connectToVm }}" _href="{{ gotoLink('/vm') }}">{{ target.name }}</a>
       </template>
       <template if="{{ !isChromeTarget }}">
         <button class="delete-button" on-click="{{ deleteVm }}">&#10006; Remove</button>
       </template>
     </span>
   </template>
 </polymer-element>
 
 <polymer-element name="vm-connect" extends="observatory-element">
   <template>
@@ skipping 53 matching lines @@
           <pre class="well">Run Chromium with:
 '--remote-debugging-port=9222'</pre>
           <hr>
         </div>
       </div>
     </div>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="vm_connect.dart"></script>