Allow Observatory debugger to switch isolates.

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

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="action_link.html">
 <link rel="import" href="curly_block.html">
 <link rel="import" href="eval_box.html">
 <link rel="import" href="function_ref.html">
 <link rel="import" href="isolate_summary.html">
 <link rel="import" href="library_ref.html">
 <link rel="import" href="nav_bar.html">
 <link rel="import" href="observatory_element.html">
 <link rel="import" href="script_inset.html">
@@ skipping 62 matching lines @@
       <div class="flex-item-20-percent"></div>
       <div class="flex-item-60-percent"><hr></div>
       <div class="flex-item-20-percent"></div>
     </div>
 
     <div class="content-centered">
       <div class="flex-row">
         <div class="flex-item-50-percent">
           <div class="memberList">
             <div class="memberItem">
+              <div class="memberName">started at</div>
+              <div class="memberValue">{{ isolate.startTime.toString() }}</div>
+            </div>
+            <div class="memberItem">
+              <div class="memberName">uptime</div>
+              <div class="memberValue">{{ isolate.upTime.toString() }}</div>
+            </div>
+            <div class="memberItem">
               <div class="memberName">root library</div>
               <div class="memberValue">
                 <library-ref ref="{{ isolate.rootLib }}"></library-ref>
               </div>
             </div>
             <div class="memberItem">
               <template if="{{ isolate.entry != null }}">
                 <div class="memberName">entry</div>
                 <div class="memberValue">
                   <function-ref ref="{{ isolate.entry }}"></function-ref>
@@ skipping 36 matching lines @@
 
     <div class="content">
       <eval-box callback="{{ eval }}"></eval-box>
     </div>
     <br><br><br><br>
     <br><br><br><br>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="isolate_view.dart"></script>