Move selector and arguments descriptor into MegamorphicCache.

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

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="observatory_element.html">
 
 <polymer-element name="service-ref" extends="observatory-element">
 </polymer-element>
 
 <polymer-element name="any-service-ref" extends="observatory-element">
 </polymer-element>
 
 <polymer-element name="object-ref" extends="service-ref">
   <template><link rel="stylesheet" href="css/shared.css">
 
     <template if="{{ ref.isObjectPool }}">
       <a on-click="{{ goto }}" _href="{{ url }}">
         <em>{{ ref.vmType }}</em> ({{ ref.length }})
       </a>
     </template>
-    <template if="{{ ref.isICData }}">
+    <template if="{{ ref.isICData || ref.isMegamorphicCache }}">
       <a on-click="{{ goto }}" _href="{{ url }}">
         <em>{{ ref.vmType }}</em> ({{ ref.selector }})
       </a>
     </template>
     <template if="{{ ref.isInstructions }}">
       <a on-click="{{ goto }}" _href="{{ url }}">
         <em>{{ ref.vmType }}</em> ({{ ref.code.name }})
       </a>
     </template>
-    <template if="{{ !(ref.isObjectPool || ref.isICData || ref.isInstructions) }}">
+    <template if="{{ !(ref.isObjectPool || ref.isICData || ref.isMegamorphicCache || ref.isInstructions) }}">
       <template if="{{ nameIsEmpty }}">
         <a on-click="{{ goto }}" _href="{{ url }}"><em>{{ ref.vmType }}</em></a>
       </template>
       <template if="{{ !nameIsEmpty }}">
         <a on-click="{{ goto }}" _href="{{ url }}"><em>{{ name }}</em></a>
       </template>
     </template>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="service_ref.dart"></script>