Make retained size human-readable.

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

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="curly_block.html">
 <link rel="import" href="eval_box.html">
 <link rel="import" href="eval_link.html">
 <link rel="import" href="field_ref.html">
 <link rel="import" href="function_ref.html">
 <link rel="import" href="instance_ref.html">
 <link rel="import" href="library_ref.html">
 <link rel="import" href="nav_bar.html">
 <link rel="import" href="observatory_element.html">
@@ skipping 120 matching lines @@
             </template>
           </div>
         </curly-block><br><br>
       </template>
       
       <template if="{{ !cls.hasNoAllocations }}">
         current instances ({{ cls.newSpace.current.instances + cls.oldSpace.current.instances }})
           <div class="memberItem">
             <div class="memberName">shallow size</div>
             <div class="memberValue">
-              {{ cls.newSpace.current.bytes + cls.oldSpace.current.bytes }}
+              {{ cls.newSpace.current.bytes + cls.oldSpace.current.bytes | formatSize }}
             </div>
           </div>
           <div class="memberItem">
             <div class="memberName">retained size</div>
             <div class="memberValue">
-              <eval-link callback="{{ retainedSize }}"></eval-link>
+              <template if="{{ retainedBytes == null }}">
+                <eval-link callback="{{ retainedSize }}"
+                           label="[calculate]">
+                </eval-link>
+              </template>
+              <template if="{{ retainedBytes != null }}">
+                {{ retainedBytes | formatSize }}
+              </template>
             </div>
           </div>
         </template>
     </div>
 
     <hr>
 
     <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="class_view.dart"></script>