Observatory: Fix bug in field overview of a class

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 81 matching lines @@
 
     <template if="{{ cls.error != null }}">
       <!-- TODO(turnidge): Don't use instance-ref for error display here -->
       <instance-ref ref="{{ cls.error }}"></instance-ref>
     </template>
 
     <hr>
 
     <div class="content">
       <template if="{{ cls.fields.isNotEmpty }}">
-        fields ({{ cls['fields'].length }})
+        fields ({{ cls.fields.length }})
         <curly-block expand="{{ cls.fields.length <= 8 }}">
           <div class="memberList">
             <template repeat="{{ field in cls.fields }}">
               <div class="memberItem">
                 <div class="memberName">
                   <field-ref ref="{{ field }}"></field-ref>
                 </div>
                 <div class="memberValue">
                   <template if="{{ field['value'] != null }}">
                     <instance-ref ref="{{ field['value'] }}"></instance-ref>
@@ skipping 72 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="class_view.dart"></script>