Remember when a variable has been expanded/unexpanded in the debugger.

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

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="curly_block.html">
 <link rel="import" href="observatory_element.html">
 <link rel="import" href="service_ref.html">
 
 <polymer-element name="instance-ref" extends="service-ref">
   <template>
     <link rel="stylesheet" href="css/shared.css">
     <style>
       .errorBox {
@@ skipping 32 matching lines @@
       </template>
 
       <template if="{{ ref.isRegExp }}">
         <a on-click="{{ goto }}" _href="{{ url }}">
           <em>{{ ref.clazz.name }}</em> ({{ ref.pattern.valueAsString }})
         </a>
       </template>
 
       <template if="{{ ref.isPlainInstance }}">
         <a on-click="{{ goto }}" _href="{{ url }}"><em>{{ ref.clazz.name }}</em></a>
-        <curly-block callback="{{ expander() }}">
+        <curly-block callback="{{ expander() }}" expandKey="{{ expandKey }}">
           <div class="memberList">
             <template repeat="{{ field in ref.fields }}">
               <div class="memberItem">
                 <div class="memberName">
                   {{ field['decl'].name }}
                 </div>
                 <div class="memberValue">
-                  <any-service-ref ref="{{ field['value'] }}"></any-service-ref>
+                  <any-service-ref ref="{{ field['value'] }}"
+                                   expandKey="{{ makeExpandKey(field['decl'].name) }}">
+                  </any-service-ref>
                 </div>
               </div>
             </template>
           </div>
         </curly-block>
       </template>
 
       <template if="{{ ref.isList }}">
         <a on-click="{{ goto }}" _href="{{ url }}"><em>{{ ref.clazz.name }}</em> ({{ ref.length }})</a>
-        <curly-block callback="{{ expander() }}">
+        <curly-block callback="{{ expander() }}" expandKey="{{ expandKey }}">
           <div class="memberList">
             <template repeat="{{ index in ref.elements.asMap().keys }}">
               <div class="memberItem">
                 <div class="memberName">[{{ index }}]</div>
                 <div class="memberValue">
-                  <any-service-ref ref="{{ ref.elements[index] }}">
+                  <any-service-ref ref="{{ ref.elements[index] }}"
+                                   expandKey="{{ makeExpandKey(index.toString()) }}">
                   </any-service-ref>
                 </div>
               </div>
             </template>
           </div>
         </curly-block>
       </template>
 
       <template if="{{ ref.isMap }}">
         <a on-click="{{ goto }}" _href="{{ url }}"><em>{{ ref.clazz.name }}</em> ({{ ref.length }})</a>
-        <curly-block callback="{{ expander() }}">
+        <curly-block callback="{{ expander() }}" expandKey="{{ expandKey }}">
           <div class="memberList">
             <template repeat="{{ association in ref.associations }}">
               <div class="memberItem">
                 <div class="memberName">
-                  [<any-service-ref ref="{{ association['key'] }}"></any-service-ref>]
+                  [<any-service-ref ref="{{ association['key'] }}"
+                                    expandKey="{{ makeExpandKey('key') }}">
+                  </any-service-ref>]
                 </div>
                 <div class="memberValue">
-                  <any-service-ref ref="{{ association['value'] }}"></any-service-ref>
+                  <any-service-ref ref="{{ association['value'] }}"
+                                   expandKey="{{ makeExpandKey('value') }}">
+                  </any-service-ref>
                 </div>
               </div>
             </template>
           </div>
         </curly-block>
       </template>
 
       <template if="{{ ref.isTypedData }}">
         <a on-click="{{ goto }}" _href="{{ url }}"><em>{{ ref.clazz.name }}</em> ({{ ref.length }})</a>
-        <curly-block callback="{{ expander() }}">
+        <curly-block callback="{{ expander() }}" expandKey="{{ expandKey }}">
           <div class="memberList">
             <template repeat="{{ index in ref.typedElements.asMap().keys }}">
               <div class="memberItem">
                 <div class="memberName">[{{ index }}]</div>
                 <div class="memberValue">{{ ref.typedElements[index].toString() }}</div>
               </div>
             </template>
           </div>
         </curly-block>
       </template>
 
       <template if="{{ ref.isMirrorReference }}">
         <a on-click="{{ goto }}" _href="{{ url }}"><em>{{ ref.clazz.name }}</em></a>
-        <curly-block callback="{{ expander() }}">
+        <curly-block callback="{{ expander() }}" expandKey="{{ expandKey }}">
           <div class="memberList">
             <div class="memberItem">
               <div class="memberName">referent</div>
               <div class="memberValue">
-                <any-service-ref ref="{{ ref.referent }}"></any-service-ref>
+                <any-service-ref ref="{{ ref.referent }}"
+                                 expandKey="{{ makeExpandKey('referent') }}">
+                </any-service-ref>
               </div>
             </div>
           </div>
         </curly-block>
       </template>
 
       <template if="{{ ref.isWeakProperty }}">
         <a on-click="{{ goto }}" _href="{{ url }}"><em>{{ ref.clazz.name }}</em></a>
-        <curly-block callback="{{ expander() }}">
+        <curly-block callback="{{ expander() }}" expandKey="{{ expandKey }}">
           <div class="memberList">
             <div class="memberItem">
               <div class="memberName">key</div>
               <div class="memberValue">
-                <any-service-ref ref="{{ ref.key }}"></any-service-ref>
+                <any-service-ref ref="{{ ref.key }}"
+                                 expandKey="{{ makeExpandKey('key') }}">
+                </any-service-ref>
               </div>
             </div>
             <div class="memberItem">
               <div class="memberName">value</div>
               <div class="memberValue">
-                <any-service-ref ref="{{ ref.value }}"></any-service-ref>
+                <any-service-ref ref="{{ ref.value }}"
+                                 expandKey="{{ makeExpandKey('value') }}">
+                </any-service-ref>
               </div>
             </div>
           </div>
         </curly-block>
       </template>
     </span>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="instance_ref.dart"></script>