Move selector and arguments descriptor into MegamorphicCache.

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

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="class_ref.html">
 <link rel="import" href="error_view.html">
 <link rel="import" href="field_ref.html">
 <link rel="import" href="function_ref.html">
 <link rel="import" href="inbound_reference.html">
 <link rel="import" href="instance_ref.html">
 <link rel="import" href="observatory_element.html">
 <link rel="import" href="object_common.html">
 <link rel="import" href="nav_bar.html">
@@ skipping 10 matching lines @@
       <nav-refresh callback="{{ refresh }}"></nav-refresh>
     </nav-bar>
 
     <div class="content">
       <object-common object="{{ megamorphicCache }}"></object-common>
 
       <br><br>
 
       <div class="memberList">
         <div class="memberItem">
+          <div class="memberName">selector</div>
+          <div class="memberValue">
+            {{ megamorphicCache.selector }}
+          </div>
+        </div>
+        <div class="memberItem">
+          <div class="memberName">argumentsDescriptor</div>
+          <div class="memberValue">
+            <any-service-ref ref="{{ megamorphicCache.argumentsDescriptor }}"></any-service-ref>
+          </div>
+        </div>
+        <div class="memberItem">
           <div class="memberName">mask</div>
           <div class="memberValue"> 
             {{ megamorphicCache.mask }}
           </div>
         </div>
         <div class="memberItem">
           <div class="memberName">buckets</div>
           <div class="memberValue">
             <any-service-ref ref="{{ megamorphicCache.buckets }}"></any-service-ref>
           </div>
         </div>
       </div>
 
     </div>
   
     <hr>
     <view-footer></view-footer>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="megamorphiccache_view.dart"></script>