Provide a logical view of VM-internal maps in Observatory.

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

Index: runtime/observatory/lib/src/elements/instance_ref.html
diff --git a/runtime/observatory/lib/src/elements/instance_ref.html b/runtime/observatory/lib/src/elements/instance_ref.html
index 0a60ee973427feec841797768dc390314193396b..6d80f6cdfebb72e210d9cd08e29ca36dac40e63f 100644
--- a/runtime/observatory/lib/src/elements/instance_ref.html
+++ b/runtime/observatory/lib/src/elements/instance_ref.html
@@ -42,8 +42,7 @@
         </a>
       </template>
 
-      <!-- TODO(rmacnak): Specialized view for maps. -->
-      <template if="{{ ref.isPlainInstance || ref.isMap }}">
+      <template if="{{ ref.isPlainInstance }}">
         <a on-click="{{ goto }}" _href="{{ url }}"><em>{{ ref.clazz.name }}</em></a>
         <curly-block callback="{{ expander() }}">
           <div class="memberList">
@@ -77,6 +76,24 @@
         </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() }}">
+          <div class="memberList">
+            <template repeat="{{ association in ref.associations }}">
+              <div class="memberItem">
+                <div class="memberName">
+                  [<any-service-ref ref="{{ association['key'] }}"></any-service-ref>]
+                </div>
+                <div class="memberValue">
+                  <any-service-ref ref="{{ association['value'] }}"></any-service-ref>
+                </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() }}">