Port metrics to RPC

runtime/observatory/lib/src/elements/metrics.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="metrics-page" extends="observatory-element">
   <template>
     <link rel="stylesheet" href="css/shared.css">
     <style>
       ul li:hover:not(.selected) {
         background-color: #FFF3E3;
@@ skipping 18 matching lines @@
               <li class="selected">
                 {{ metric.name }}
               </li>
             </template>
             <template if="{{ metric != selectedMetric }}">
               <li on-click="{{ selectMetric }}" data-id="{{ metric.id }}">
                 {{ metric.name }}
               </li>
             </template>
           </template>
-          <template repeat="{{ metric in isolate.vmMetrics.values }}">
+          <template repeat="{{ metric in isolate.nativeMetrics.values }}">
             <template if="{{ metric == selectedMetric }}">
               <li class="selected">
                 {{ metric.name }}
               </li>
             </template>
             <template if="{{ metric != selectedMetric }}">
               <li on-click="{{ selectMetric }}" data-id="{{ metric.id }}">
                 {{ metric.name }}
               </li>
             </template>
@@ skipping 78 matching lines @@
       .graph {
         min-height: 600px;
       }
     </style>
     <div id="graph" class="graph">
     </div>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="metrics.dart"></script>